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Color

ContentsArticles

Color 1

Color Theory 12

Color space 12Color theory 16Additive color 23Subtractive color 25

Mixing Color 28

Color mixing 28Primary color 29Colorfulness 35Dichromatism 39Hue 41Tints and shades 44Lightness 46

Perception of Color 50

Opponent process 50Impossible colors 53Color vision 55Visual perception 66

Visual Color 72

List of colors 72Web colors 99

ReferencesArticle Sources and Contributors 110Image Sources, Licenses and Contributors 113

Article LicensesLicense 115

Color 1

Color

Colored pencils

Color or colour (see spelling differences) isthe visual perceptual property correspondingin humans to the categories called red,green, blue and others. Color derives fromthe spectrum of light (distribution of lightpower versus wavelength) interacting in theeye with the spectral sensitivities of the lightreceptors. Color categories and physicalspecifications of color are also associatedwith objects, materials, light sources, etc.,based on their physical properties such aslight absorption, reflection, or emissionspectra. By defining a color space, colorscan be identified numerically by theircoordinates.

Because perception of color stems from the varying spectral sensitivity of different types of cone cells in the retina todifferent parts of the spectrum, colors may be defined and quantified by the degree to which they stimulate thesecells. These physical or physiological quantifications of color, however, do not fully explain the psychophysicalperception of color appearance.

The science of color is sometimes called chromatics, colorimetry, or simply color science. It includes the perceptionof color by the human eye and brain, the origin of color in materials, color theory in art, and the physics ofelectromagnetic radiation in the visible range (that is, what we commonly refer to simply as light).

Physics

Continuous optical spectrum rendered into the sRGB color space.

The colors of the visible light spectrum[1]

color wavelength interval frequency interval

red ~ 700–635 nm ~ 430–480 THz

orange ~ 635–590 nm ~ 480–510 THz

yellow ~ 590–560 nm ~ 510–540 THz

green ~ 560–490 nm ~ 540–610 THz

blue ~ 490–450 nm ~ 610–670 THz

violet ~ 450–400 nm ~ 670–750 THz

Color 2

Color, wavelength, frequency and energy of light

Color (nm) (THz) (μm−1) (eV) (kJ mol−1)

Infrared >1000 <300 <1.00 <1.24 <120

Red 700 428 1.43 1.77 171

Orange 620 484 1.61 2.00 193

Yellow 580 517 1.72 2.14 206

Green 530 566 1.89 2.34 226

Blue 470 638 2.13 2.64 254

Violet 420 714 2.38 2.95 285

Near ultraviolet 300 1000 3.33 4.15 400

Far ultraviolet <200 >1500 >5.00 >6.20 >598

Electromagnetic radiation is characterized by its wavelength (or frequency) and its intensity. When the wavelength iswithin the visible spectrum (the range of wavelengths humans can perceive, approximately from 390 nm to 750 nm),it is known as "visible light".Most light sources emit light at many different wavelengths; a source's spectrum is a distribution giving its intensityat each wavelength. Although the spectrum of light arriving at the eye from a given direction determines the colorsensation in that direction, there are many more possible spectral combinations than color sensations. In fact, onemay formally define a color as a class of spectra that give rise to the same color sensation, although such classeswould vary widely among different species, and to a lesser extent among individuals within the same species. Ineach such class the members are called metamers of the color in question.

Spectral colorsThe familiar colors of the rainbow in the spectrum – named using the Latin word for appearance or apparition byIsaac Newton in 1671 – include all those colors that can be produced by visible light of a single wavelength only, thepure spectral or monochromatic colors. The table at right shows approximate frequencies (in terahertz) andwavelengths (in nanometers) for various pure spectral colors. The wavelengths are measured in air or vacuum (seerefraction).The color table should not be interpreted as a definitive list – the pure spectral colors form a continuous spectrum,and how it is divided into distinct colors linguistically is a matter of culture and historical contingency (althoughpeople everywhere have been shown to perceive colors in the same way[2] ). A common list identifies six mainbands: red, orange, yellow, green, blue, and violet. Newton's conception included a seventh color, indigo, betweenblue and violet. Optical scientists Hardy and Perrin list indigo as between 446 and 464 nm wavelength.[3]

The intensity of a spectral color, relative to the context in which it is viewed, may alter its perception considerably;for example, a low-intensity orange-yellow is brown, and a low-intensity yellow-green is olive-green.For discussion of non-spectral colors, see below.

Color of objectsThe color of an object depends on both the physics of the object in its environment and the characteristics of the perceiving eye and brain. Physically, objects can be said to have the color of the light leaving their surfaces, which normally depends on the spectrum of the incident illumination and the reflectance properties of the surface, as well as potentially on the angles of illumination and viewing. Some objects not only reflect light, but also transmit light or emit light themselves (see below), which contribute to the color also. And a viewer's perception of the object's color

Color 3

depends not only on the spectrum of the light leaving its surface, but also on a host of contextual cues, so that thecolor tends to be perceived as relatively constant: that is, relatively independent of the lighting spectrum, viewingangle, etc. This effect is known as color constancy.

The upper disk and the lower disk have exactly the same objectivecolor, and are in identical gray surroundings; based on contextdifferences, humans perceive the squares as having differentreflectances, and may interpret the colors as different color

categories; see same color illusion.

Some generalizations of the physics can be drawn,neglecting perceptual effects for now:• Light arriving at an opaque surface is either

reflected "specularly" (that is, in the manner of amirror), scattered (that is, reflected with diffusescattering), or absorbed – or some combination ofthese.

• Opaque objects that do not reflect specularly (whichtend to have rough surfaces) have their colordetermined by which wavelengths of light theyscatter more and which they scatter less (with thelight that is not scattered being absorbed). If objectsscatter all wavelengths, they appear white. If theyabsorb all wavelengths, they appear black.

• Opaque objects that specularly reflect light ofdifferent wavelengths with different efficiencieslook like mirrors tinted with colors determined bythose differences. An object that reflects some fraction of impinging light and absorbs the rest may look black butalso be faintly reflective; examples are black objects coated with layers of enamel or lacquer.

• Objects that transmit light are either translucent (scattering the transmitted light) or transparent (not scattering thetransmitted light). If they also absorb (or reflect) light of various wavelengths differentially, they appear tintedwith a color determined by the nature of that absorption (or that reflectance).

• Objects may emit light that they generate themselves, rather than merely reflecting or transmitting light. Theymay do so because of their elevated temperature (they are then said to be incandescent), as a result of certainchemical reactions (a phenomenon called chemoluminescence), or for other reasons (see the articlesPhosphorescence and List of light sources).

• Objects may absorb light and then as a consequence emit light that has different properties. They are then calledfluorescent (if light is emitted only while light is absorbed) or phosphorescent (if light is emitted even after lightceases to be absorbed; this term is also sometimes loosely applied to light emitted because of chemical reactions).

For further treatment of the color of objects, see structural color, below.To summarize, the color of an object is a complex result of its surface properties, its transmission properties, and itsemission properties, all of which factors contribute to the mix of wavelengths in the light leaving the surface of theobject. The perceived color is then further conditioned by the nature of the ambient illumination, and by the colorproperties of other objects nearby, via the effect known as color constancy and via other characteristics of theperceiving eye and brain.

Color 4

Perception

Normalized typical human cone cell responses (S, M, and L types) tomonochromatic spectral stimuli

Development of theories of colorvision

Although Aristotle and other ancientscientists had already written on the natureof light and color vision, it was not untilNewton that light was identified as thesource of the color sensation. In 1810,Goethe published his comprehensive Theoryof Colors. In 1801 Thomas Young proposedhis trichromatic theory, based on theobservation that any color could be matchedwith a combination of three lights. Thistheory was later refined by James ClerkMaxwell and Hermann von Helmholtz. AsHelmholtz puts it, "the principles ofNewton's law of mixture wereexperimentally confirmed by Maxwell in1856. Young's theory of color sensations, like so much else that this marvellous investigator achieved in advance ofhis time, remained unnoticed until Maxwell directed attention to it."[4]

At the same time as Helmholtz, Ewald Hering developed the opponent process theory of color, noting that colorblindness and afterimages typically come in opponent pairs (red-green, blue-orange, yellow-purple, andblack-white). Ultimately these two theories were synthesized in 1957 by Hurvich and Jameson, who showed thatretinal processing corresponds to the trichromatic theory, while processing at the level of the lateral geniculatenucleus corresponds to the opponent theory.[5]

In 1931, an international group of experts known as the Commission internationale de l'éclairage (CIE) developed amathematical color model, which mapped out the space of observable colors and assigned a set of three numbers toeach.

Color 5

Color in the eye

This image (when viewed in full size, 1000 pixelswide) contains 1 million pixels, each of a

different color. The human eye can distinguishabout 10 million different colors.[6]

The ability of the human eye to distinguish colors is based upon thevarying sensitivity of different cells in the retina to light of differentwavelengths. Humans being trichromatic, the retina contains threetypes of color receptor cells, or cones. One type, relatively distinctfrom the other two, is most responsive to light that we perceive asviolet, with wavelengths around 420 nm; cones of this type aresometimes called short-wavelength cones, S cones, or blue cones. Theother two types are closely related genetically and chemically. One ofthem, sometimes called long-wavelength cones, L cones, or red cones,is most sensitive to light we perceive as greenish yellow, withwavelengths around 564 nm; the other type, known asmiddle-wavelength cones, M cones, or green cones is most sensitive tolight perceived as green, with wavelengths around 534 nm.

Light, no matter how complex its composition of wavelengths, isreduced to three color components by the eye. For each location in thevisual field, the three types of cones yield three signals based on the extent to which each is stimulated. Theseamounts of stimulation are sometimes called tristimulus values.

The response curve as a function of wavelength for each type of cone is illustrated above. Because the curvesoverlap, some tristimulus values do not occur for any incoming light combination. For example, it is not possible tostimulate only the mid-wavelength (so-called "green") cones; the other cones will inevitably be stimulated to somedegree at the same time. The set of all possible tristimulus values determines the human color space. It has beenestimated that humans can distinguish roughly 10 million different colors.[6]

The other type of light-sensitive cell in the eye, the rod, has a different response curve. In normal situations, whenlight is bright enough to strongly stimulate the cones, rods play virtually no role in vision at all.[7] On the other hand,in dim light, the cones are understimulated leaving only the signal from the rods, resulting in a colorless response.(Furthermore, the rods are barely sensitive to light in the "red" range.) In certain conditions of intermediateillumination, the rod response and a weak cone response can together result in color discriminations not accountedfor by cone responses alone. These effects, combined, are summarized also in the Kruithof curve, that describes thechange of color perception and pleasingness of light as function of temperature and intensity.

Color 6

Color in the brain

The visual dorsal stream (green) and ventral stream (purple) are shown. The ventralstream is responsible for color perception.

While the mechanisms of color vision at thelevel of the retina are well-described interms of tristimulus values (see above),color processing after that point is organizeddifferently. A dominant theory of colorvision proposes that color information istransmitted out of the eye by three opponentprocesses, or opponent channels, eachconstructed from the raw output of thecones: a red-green channel, a blue-yellowchannel and a black-white "luminance"channel. This theory has been supported byneurobiology, and accounts for the structureof our subjective color experience.Specifically, it explains why we cannotperceive a "reddish green" or "yellowishblue," and it predicts the color wheel: it is the collection of colors for which at least one of the two color channelsmeasures a value at one of its extremes.

The exact nature of color perception beyond the processing already described, and indeed the status of color as afeature of the perceived world or rather as a feature of our perception of the world, is a matter of complex andcontinuing philosophical dispute (see qualia).

Nonstandard color perception

Color deficiency

If one or more types of a person's color-sensing cones are missing or less responsive than normal to incoming light,that person can distinguish fewer colors and is said to be color deficient or color blind (though this latter term can bemisleading; almost all color deficient individuals can distinguish at least some colors). Some kinds of colordeficiency are caused by anomalies in the number or nature of cones in the retina. Others (like central or corticalachromatopsia) are caused by neural anomalies in those parts of the brain where visual processing takes place.

Tetrachromacy

While most humans are trichromatic (having three types of color receptors), many animals, known as tetrachromats,have four types. These include some species of spiders, most marsupials, birds, reptiles, and many species of fish.Other species are sensitive to only two axes of color or do not perceive color at all; these are called dichromats andmonochromats respectively. A distinction is made between retinal tetrachromacy (having four pigments in conecells in the retina, compared to three in trichromats) and functional tetrachromacy (having the ability to makeenhanced color discriminations based on that retinal difference). As many as half of all women are retinaltetrachromats.[8] :p.256 The phenomenon arises when an individual receives two slightly different copies of the genefor either the medium- or long-wavelength cones, which are carried on the x-chromosome. To have two differentgenes, a person must have two x-chromosomes, which is why the phenomenon only occurs in women.[8] For some ofthese retinal tetrachromats, color discriminations are enhanced, making them functional tetrachromats.[8]

Color 7

Synesthesia

In certain forms of synesthesia, perceiving letters and numbers (grapheme–color synesthesia) or hearing musicalsounds (music–color synesthesia) will lead to the unusual additional experiences of seeing colors. Behavioral andfunctional neuroimaging experiments have demonstrated that these color experiences lead to changes in behavioraltasks and lead to increased activation of brain regions involved in color perception, thus demonstrating their reality,and similarity to real color percepts, albeit evoked through a non-standard route.

Afterimages

An example of an Afterimage

After exposure to strong light in their sensitivity range,photoreceptors of a given type become desensitized. For a fewseconds after the light ceases, they will continue to signal lessstrongly than they otherwise would. Colors observed duringthat period will appear to lack the color component detectedby the desensitized photoreceptors. This effect is responsiblefor the phenomenon of afterimages, in which the eye maycontinue to see a bright figure after looking away from it, butin a complementary color.

Afterimage effects have also been utilized by artists, includingVincent van Gogh.

Color constancy

There is an interesting phenomenon which occurs when anartist uses a limited color palette: the eye tends to compensate by seeing any gray or neutral color as the color whichis missing from the color wheel. For example, in a limited palette consisting of red, yellow, black and white, amixture of yellow and black will appear as a variety of green, a mixture of red and black will appear as a variety ofpurple, and pure gray will appear bluish.[9]

The trichromatic theory discussed above is strictly true when the visual system is in a fixed state of adaptation. Inreality, the visual system is constantly adapting to changes in the environment and compares the various colors in ascene to reduce the effects of the illumination. If a scene is illuminated with one light, and then with another, as longas the difference between the light sources stays within a reasonable range, the colors in the scene appear relativelyconstant to us. This was studied by Edwin Land in the 1970s and led to his retinex theory of color constancy.It should be noted, that both phenomena described above are readily explained and mathematical modeled withmodern theories of chromatic adaptation and color appearance (e.g. CIECAM02, iCAM).[10] There is no need todismiss the trichromatic theory of vision, but rather it must be enhanced with an understanding of how the visualsystem adapts (adjusts) to changes in the viewing environment.

Color namingColors vary in several different ways, including hue (shades of red, orange, yellow, green, blue, and violet),saturation, brightness, and gloss. Some color words are derived from the name of an object of that color, such as"orange" or "salmon", while others are abstract, like "red".Different cultures have different terms for colors, and may also assign some color names to slightly different parts ofthe spectrum: for instance, the Chinese character 青 (rendered as qīng in Mandarin and ao in Japanese) has ameaning that covers both blue and green; blue and green are traditionally considered shades of "青." South Korea, onthe other hand, differentiates between blue and green by using "綠 (녹)" for green and "靑 (청)" for blue.

Color 8

In the 1969 study Basic Color Terms: Their Universality and Evolution, Brent Berlin and Paul Kay describe a patternin naming "basic" colors (like "red" but not "red-orange" or "dark red" or "blood red", which are "shades" of red).All languages that have two "basic" color names distinguish dark/cool colors from bright/warm colors. The nextcolors to be distinguished are usually red and then yellow or green. All languages with six "basic" colors includeblack, white, red, green, blue and yellow. The pattern holds up to a set of twelve: black, gray, white, pink, red,orange, yellow, green, blue, purple, brown, and azure (distinct from blue in Russian and Italian but not English).

AssociationsIndividual colors have a variety of cultural associations such as national colors (in general described in individualcolor articles and color symbolism). The field of color psychology attempts to identify the effects of color on humanemotion and activity. Chromotherapy is a form of alternative medicine attributed to various Eastern traditions.Colors have different associations in different countries and cultures.[11]

Different colors have been demonstrated to have affects on cognition. For example, researchers at the University ofLinz in Austria demonstrated that the color red significantly decreases cognitive functioning in men.[12]

Spectral colors and color reproduction

The CIE 1931 color space chromaticity diagram. The outer curvedboundary is the spectral (or monochromatic) locus, with wavelengths

shown in nanometers. Note that the colors depicted depend on thecolor space of the device on which you are viewing the image, and

therefore may not be a strictly accurate representation of the color ata particular position, and especially not for monochromatic colors.

Most light sources are mixtures of various wavelengthsof light. However, many such sources can still have aspectral color insofar as the eye cannot distinguishthem from monochromatic sources. For example, mostcomputer displays reproduce the spectral color orangeas a combination of red and green light; it appearsorange because the red and green are mixed in the rightproportions to allow the eye's red and green cones torespond the way they do to orange.A useful concept in understanding the perceived colorof a non-monochromatic light source is the dominantwavelength, which identifies the single wavelength oflight that produces a sensation most similar to the lightsource. Dominant wavelength is roughly akin to hue.

There are many color perceptions that by definitioncannot be pure spectral colors due to desaturation orbecause they are purples (mixtures of red and violetlight, from opposite ends of the spectrum). Someexamples of necessarily non-spectral colors are theachromatic colors (black, gray and white) and colorssuch as pink, tan, and magenta.

Two different light spectra that have the same effect onthe three color receptors in the human eye will beperceived as the same color. This is exemplified by the white light emitted by fluorescent lamps, which typically hasa spectrum of a few narrow bands, while daylight has a continuous spectrum. The human eye cannot tell thedifference between such light spectra just by looking into the light source, although reflected colors from objects canlook different. (This is often exploited e.g. to make fruit or tomatoes look more intensely red.)

Similarly, most human color perceptions can be generated by a mixture of three colors called primaries. This is used to reproduce color scenes in photography, printing, television and other media. There are a number of methods or

Color 9

color spaces for specifying a color in terms of three particular primary colors. Each method has its advantages anddisadvantages depending on the particular application.No mixture of colors, though, can produce a fully pure color perceived as completely identical to a spectral color,although one can get very close for the longer wavelengths, where the chromaticity diagram above has a nearlystraight edge. For example, mixing green light (530 nm) and blue light (460 nm) produces cyan light that is slightlydesaturated, because response of the red color receptor would be greater to the green and blue light in the mixturethan it would be to a pure cyan light at 485 nm that has the same intensity as the mixture of blue and green.Because of this, and because the primaries in color printing systems generally are not pure themselves, the colorsreproduced are never perfectly saturated colors, and so spectral colors cannot be matched exactly. However, naturalscenes rarely contain fully saturated colors, thus such scenes can usually be approximated well by these systems. Therange of colors that can be reproduced with a given color reproduction system is called the gamut. The CIEchromaticity diagram can be used to describe the gamut.Another problem with color reproduction systems is connected with the acquisition devices, like cameras orscanners. The characteristics of the color sensors in the devices are often very far from the characteristics of thereceptors in the human eye. In effect, acquisition of colors that have some special, often very "jagged," spectracaused for example by unusual lighting of the photographed scene can be relatively poor.Species that have color receptors different from humans, e.g. birds that may have four receptors, can differentiatesome colors that look the same to a human. In such cases, a color reproduction system 'tuned' to a human withnormal color vision may give very inaccurate results for the other observers.The different color response of different devices can be problematic if not properly managed. For color informationstored and transferred in digital form, color management techniques, such as those based on ICC profiles, can help toavoid distortions of the reproduced colors. Color management does not circumvent the gamut limitations ofparticular output devices, but can assist in finding good mapping of input colors into the gamut that can bereproduced.

Pigments and reflective mediaPigments are chemicals that selectively absorb and reflect different spectra of light. When a surface is painted with apigment, light hitting the surface is reflected, minus some wavelengths. This subtraction of wavelengths produces theappearance of different colors. Most paints are a blend of several chemical pigments, intended to produce a reflectionof a given color.Pigment manufacturers assume the source light will be white, or of roughly equal intensity across the spectrum. Ifthe light is not a pure white source (as in the case of nearly all forms of artificial lighting), the resulting spectrum willappear a slightly different color. Red paint, viewed under blue light, may appear black. Red paint is red because itreflects only the red components of the spectrum. Blue light, containing none of these, will create no reflection fromred paint, creating the appearance of black.

Structural colorStructural colors are colors caused by interference effects rather than by pigments. Color effects are produced when a material is scored with fine parallel lines, formed of one or more parallel thin layers, or otherwise composed of microstructures on the scale of the color's wavelength. If the microstructures are spaced randomly, light of shorter wavelengths will be scattered preferentially to produce Tyndall effect colors: the blue of the sky (Rayleigh scattering, caused by structures much smaller than the wavelength of light, in this case air molecules), the luster of opals, and the blue of human irises. If the microstructures are aligned in arrays, for example the array of pits in a CD, they behave as a diffraction grating: the grating reflects different wavelengths in different directions due to interference phenomena, separating mixed "white" light into light of different wavelengths. If the structure is one or

Color 10

more thin layers then it will reflect some wavelengths and transmit others, depending on the layers' thickness.Structural color is studied in the field of thin-film optics. A layman's term that describes particularly the mostordered or the most changeable structural colors is iridescence. Structural color is responsible for the blues andgreens of the feathers of many birds (the blue jay, for example), as well as certain butterfly wings and beetle shells.Variations in the pattern's spacing often give rise to an iridescent effect, as seen in peacock feathers, soap bubbles,films of oil, and mother of pearl, because the reflected color depends upon the viewing angle. Numerous scientistshave carried out research in butterfly wings and beetle shells, including Isaac Newton and Robert Hooke. Since1942, electron micrography has been used, advancing the development of products that exploit structural color, suchas "photonic" cosmetics.[13]

Additional terms• Colorfulness, chroma, purity, or saturation: how "intense" or "concentrated" a color is. Technical definitions

distinguish between colorfulness, chroma, and saturation as distinct perceptual attributes and include purity as aphysical quantity. These terms, and others related to light and color are internationally agreed upon and publishedin the CIE Lighting Vocabulary.[14] More readily available texts on colorimetry also define and explain theseterms.[15] [16]

• Dichromatism: a phenomenon where the hue is dependent on concentration and/or thickness of the absorbingsubstance.

• Hue: the color's direction from white, for example in a color wheel or chromaticity diagram.• Shade: a color made darker by adding black.• Tint: a color made lighter by adding white.• Value, brightness, lightness, or luminosity: how light or dark a color is.

References[1] Craig F. Bohren (2006). Fundamentals of Atmospheric Radiation: An Introduction with 400 Problems (http:/ / books. google. com/

?id=1oDOWr_yueIC& pg=PA214& lpg=PA214& dq=indigo+ spectra+ blue+ violet+ date:1990-2007). Wiley-VCH. ISBN 3527405038. .[2] Berlin, B. and Kay, P., Basic Color Terms: Their Universality and Evolution, Berkeley: University of California Press, 1969.[3] Arthur C. Hardy and Fred H. Perrin. The Principles of Optics. (http:/ / apps. isiknowledge. com/ full_record. do?product=UA&

search_mode=GeneralSearch& qid=22& SID=2EdCK2KejLbni4FJpgB& page=1& doc=1& colname=BIOSIS) McGraw-Hill Book Co., Inc.,New York. 1932.

[4] Hermann von Helmholtz, Physiological Optics – The Sensations of Vision, 1866, as translated in Sources of Color Science, David L.MacAdam, ed., Cambridge: MIT Press, 1970.

[5] Palmer, S.E. (1999). Vision Science: Photons to Phenomenology, Cambridge, MA: MIT Press. ISBN 0-262-16183-4.[6] Judd, Deane B.; Wyszecki, Günter (1975). Color in Business, Science and Industry. Wiley Series in Pure and Applied Optics (third ed.). New

York: Wiley-Interscience. p. 388. ISBN 0471452122.[7] "Under well-lit viewing conditions (photopic vision), cones  ...are highly active and rods are inactive." Hirakawa, K.; Parks, T.W. (2005).

"Chromatic Adaptation and White-Balance Problem" (http:/ / www. accidentalmark. com/ research/ papers/ Hirakawa05WBICIP. pdf). IEEEICIP. doi:10.1109/ICIP.2005.1530559. .

[8] Jameson, K. A., Highnote, S. M., & Wasserman, L. M. (2001). "Richer color experience in observers with multiple photopigment opsingenes." (http:/ / www. klab. caltech. edu/ cns186/ papers/ Jameson01. pdf) (PDF). Psychonomic Bulletin and Review 8 (2): 244–261.doi:10.1038/351652a0. PMID 1904993. .

[9] Depauw, Robert C.. "United States Patent" (http:/ / www. google. com/ patents?hl=en& lr=& vid=USPAT3815265& id=tSEzAAAAEBAJ&oi=fnd& dq=mixing+ paint+ colors& printsec=abstract#v=onepage& q=mixing paint colors& f=false). . Retrieved 20 March 2011.

[10] M.D. Fairchild, Color Appearance Models (http:/ / www. wiley. com/ WileyCDA/ WileyTitle/ productCd-0470012161. html), 2nd Ed.,Wiley, Chichester (2005).

[11] "Chart: Color Meanings by Culture" (http:/ / www. globalization-group. com/ edge/ resources/ color-meanings-by-culture/ ). . Retrieved2010-06-29.

[12] Gnambs, Timo; Appel, Markus; Batinic, Bernad. (2010). Color red in web-based knowledge testing. Computers in Human Behavior, 26,p1625-1631.

[13] "Economic and Social Research Council - Science in the Dock, Art in the Stocks" (http:/ / www. esrc. ac. uk/ ESRCInfoCentre/ about/ CI/events/ FSS/ 2006/ science. aspx?ComponentId=14867& SourcePageId=14865). . Retrieved 2007-10-07.

[14] CIE Pub. 17-4, International Lighting Vocabulary (http:/ / www. cie. co. at/ publ/ abst/ 17-4-89. html), 1987.

Color 11

[15] R.S. Berns, Principles of Color Technology (http:/ / www. wiley. com/ WileyCDA/ WileyTitle/ productCd-047119459X. html), 3rd Ed.,Wiley, New York (2001).

[16] M.D. Fairchild, Color Appearance Models (http:/ / www. wiley. com/ WileyCDA/ WileyTitle/ productCd-0470012161. html), 2nd Ed.,Wiley, Chichester (2005).

External links and sources• Bibliography Database on Color Theory (http:/ / www. fadu. uba. ar/ sitios/ sicyt/ color/ bib. htm), Buenos Aires

University• Color (http:/ / plato. stanford. edu/ entries/ color) entry by Barry Maund in the Stanford Encyclopedia of

Philosophy• Why Should Engineers and Scientists Be Worried About Color? (http:/ / www. research. ibm. com/ people/ l/

lloydt/ color/ color. HTM)• Robert Ridgway's A Nomenclature of Colors (1886) (http:/ / lhldigital. lindahall. org/ cdm4/ document.

php?CISOROOT=/ nat_hist& CISOPTR=1733& REC=1) and Color Standards and Color Nomenclature (1912)(http:/ / lhldigital. lindahall. org/ cdm4/ document. php?CISOROOT=/ nat_hist& CISOPTR=1559& REC=1) -text-searchable digital facsimiles at Linda Hall Library

• Albert Henry Munsell's A Color Notation (http:/ / www. gutenberg. org/ files/ 26054/ 26054-h/ 26054-h. htm),(1907) at Project Gutenberg

• AIC (http:/ / www. aic-color. org/ ), International Colour Association

12

Color Theory

Color space

A comparison of the chromaticities enclosed bysome color spaces.

A color model is an abstract mathematical model describing the waycolors can be represented as tuples of numbers, typically as three orfour values or color components (e.g. RGB and CMYK are colormodels). However, a color model with no associated mapping functionto an absolute color space is a more or less arbitrary color system withno connection to any globally understood system of colorinterpretation.

Adding a certain mapping function between the color model and acertain reference color space results in a definite "footprint" within thereference color space. This "footprint" is known as a gamut, and, incombination with the color model, defines a new color space. Forexample, Adobe RGB and sRGB are two different absolute colorspaces, both based on the RGB model.

In the most generic sense of the definition above, color spaces can bedefined without the use of a color model. These spaces, such as Pantone, are in effect a given set of names ornumbers which are defined by the existence of a corresponding set of physical color swatches. This article focuseson the mathematical model concept.

Understanding the concept

A comparison of RGB and CMYK color models.This image demonstrates the difference between

how colors will look on a computer monitor(RGB) compared to how they will reproduce in a

CMYK print process.

A wide range of colors can be created by the primary colors of pigment(cyan (C), magenta (M), yellow (Y), and black (K)). Those colors thendefine a specific color space. To create a three-dimensionalrepresentation of a color space, we can assign the amount of magentacolor to the representation's X axis, the amount of cyan to its Y axis,and the amount of yellow to its Z axis. The resulting 3-D spaceprovides a unique position for every possible color that can be createdby combining those three pigments.

However, this is not the only possible color space. For instance, whencolors are displayed on a computer monitor, they are usually defined inthe RGB (red, green and blue) color space. This is another way ofmaking nearly the same colors (limited by the reproduction medium,such as the phosphor (CRT) or filters and backlight (LCD)), and red,green and blue can be considered as the X, Y and Z axes. Another wayof making the same colors is to use their Hue (X axis), their Saturation(Y axis), and their brightness Value (Z axis). This is called the HSVcolor space. Many color spaces can be represented as three-dimensional (X,Y,Z) values in this manner, but somehave more, or fewer dimensions, and some, such as Pantone, cannot be represented in this way at all.

Color space 13

NotesWhen formally defining a color space, the usual reference standard is the CIELAB or CIEXYZ color spaces, whichwere specifically designed to encompass all colors the average human can see.Since "color space" is a more specific term for a certain combination of a color model plus a mapping function, theterm "color space" tends to be used to also identify color models, since identifying a color space automaticallyidentifies the associated color model. Informally, the two terms are often used interchangeably, though this is strictlyincorrect. For example, although several specific color spaces are based on the RGB model, there is no such thing asthe RGB color space.Since any color space defines colors as a function of the absolute reference frame, color spaces, along with deviceprofiling, allow reproducible representations of color, in both analogue and digital representations.

ConversionColor space conversion is the translation of the representation of a color from one basis to another. This typicallyoccurs in the context of converting an image that is represented in one color space to another color space, the goalbeing to make the translated image look as similar as possible to the original.

DensityThe RGB color model is implemented in different ways, depending on the capabilities of the system used. By far themost common general-used incarnation as of 2006 is the 24-bit implementation, with 8 bits, or 256 discrete levels ofcolor per channel. Any color space based on such a 24-bit RGB model is thus limited to a range of 256×256×256 ≈16.7 million colors. Some implementations use 16 bits per component for 48 bits total, resulting in the same gamutwith a larger number of distinct colors. This is especially important when working with wide-gamut color spaces(where most of the more common colors are located relatively close together), or when a large number of digitalfiltering algorithms are used consecutively. The same principle applies for any color space based on the same colormodel, but implemented in different bit depths.

Color space 14

Partial list of color spacesCIE 1931 XYZ color space was one of the first attempts to produce a color space based on measurements of humancolor perception (earlier efforts were by James Clerk Maxwell, König & Dieterici, and Abney at Imperial College)[1]

and it is the basis for almost all other color spaces. Derivatives of the CIE XYZ space include CIELUV, CIEUVW,and CIELAB.

Generic color models

Additive color mixing: Three overlapping lightbulbs ina vacuum, adding together to create white.

Subtractive color mixing: Three splotches of paint onwhite paper, subtracting together to turn the paper

black.

RGB uses additive color mixing, because it describes what kind oflight needs to be emitted to produce a given color. Light is addedtogether to create form from out of the darkness. RGB storesindividual values for red, green and blue. RGBA is RGB with anadditional channel, alpha, to indicate transparency.

Common color spaces based on the RGB model include sRGB,Adobe RGB and ProPhoto RGB.

CMYK uses subtractive color mixing used in the printing process,because it describes what kind of inks need to be applied so thelight reflected from the substrate and through the inks produces agiven color. One starts with a white substrate (canvas, page, etc.),and uses ink to subtract color from white to create an image.CMYK stores ink values for cyan, magenta, yellow and black.There are many CMYK color spaces for different sets of inks,substrates, and press characteristics (which change the dot gain ortransfer function for each ink and thus change the appearance).

YIQ was formerly used in NTSC (North America, Japan andelsewhere) television broadcasts for historical reasons. Thissystem stores a luminance value with two chrominance values,corresponding approximately to the amounts of blue and red in thecolor. It is similar to the YUV scheme used in most video capturesystems[2] and in PAL (Australia, Europe, except France, whichuses SECAM) television, except that the YIQ color space isrotated 33° with respect to the YUV color space. The YDbDrscheme used by SECAM television is rotated in another way.

YPbPr is a scaled version of YUV. It is most commonly seen in itsdigital form, YCbCr, used widely in video and image compressionschemes such as MPEG and JPEG.

xvYCC is a new international digital video color space standardpublished by the IEC (IEC 61966-2-4). It is based on the ITUBT.601 and BT.709 standards but extends the gamut beyond the R/G/B primaries specified in those standards.

HSV (hue, saturation, value), also known as HSB (hue, saturation, brightness) is often used by artists because it isoften more natural to think about a color in terms of hue and saturation than in terms of additive or subtractive colorcomponents. HSV is a transformation of an RGB colorspace, and its components and colorimetry are relative to theRGB colorspace from which it was derived.HSL (hue, saturation, lightness/luminance), also known as HLS or HSI (hue, saturation, intensity) is quite similar to HSV, with "lightness" replacing "brightness". The difference is that the brightness of a pure color is equal to the

Color space 15

brightness of white, while the lightness of a pure color is equal to the lightness of a medium gray.

Commercial color spaces• Munsell color system• Natural Color System (NCS)

Special-purpose color spaces• The RG Chromaticity space is used in Computer vision applications. It shows the color of light (red, yellow,

green etc.), but not its intensity (dark, bright).

Obsolete color spacesEarly color spaces had two components. They largely ignored blue light because the added complexity of a3-component process provided only a marginal increase in fidelity when compared to the jump from monochrome to2-component color.• RG for early Technicolor film• RGK for early color printing

References[1] William David Wright, 50 years of the 1931 CIE Standard Observer. Die Farbe, 29:4/6 (1981).[2] Dean Anderson. "Color Spaces in Frame Grabbers: RGB vs. YUV" (http:/ / www. sensoray. com/ support/ frame_grabber_capture_modes.

htm). . Retrieved 2008-04-08.

External links• Color FAQ (http:/ / www. poynton. com/ ColorFAQ. html), Charles Poynton• FAQ about color physics (http:/ / www. colourware. co. uk/ cpfaq. htm), Stephen Westland• Color Science (http:/ / www. physics. sfasu. edu/ astro/ color. html), Dan Bruton• Color Spaces (http:/ / www4. ncsu. edu/ ~rgkuehni/ PDFs/ ColSp. pdf), Rolf G. Kuehni (October 2003)• Colour spaces - perceptual, historical and applicational background (http:/ / ldos. fe. uni-lj. si/ docs/ documents/

20030929092037_markot. pdf), Marko Tkalčič (2003)• Color formats (http:/ / www. equasys. de/ colorformat. html) for image and video processing - Color conversion

(http:/ / www. equasys. de/ colorconversion. html) between RGB, YUV, YCbCr and YPbPr.• C library (http:/ / pixfc-sse. googlecode. com) of SSE-optimised color format conversions.• Konica Minolta Sensing: Precise Color Communication (http:/ / www2. konicaminolta. eu/ eu/ Measuring/ pcc/

en/ index. html)

Color theory 16

Color theoryIn the visual arts, color theory is a body of practical guidance to color mixing and the visual impacts of specificcolor combination. There are also definitions (or categories) of colors based on the color wheel: Primary, Secondaryand Tertiary Colors . Although color theory principles first appeared in the writings of Leone Battista Alberti(c.1435) and the notebooks of Leonardo da Vinci (c.1490), a tradition of "colory theory" began in the 18th century,initially within a partisan controversy around Isaac Newton's theory of color (Opticks, 1704) and the nature ofso-called primary colors. From there it developed as an independent artistic tradition with only superficial referenceto colorimetry and vision science.

Color abstractions

Additive color mixing Subtractive color mixing

The foundations of pre-20th-century color theory were built around "pure" or ideal colors, characterized by sensoryexperiences rather than attributes of the physical world. This has led to a number of inaccuracies in traditional colortheory principles that are not always remedied in modern formulations.The most important problem has been a confusion between the behavior of light mixtures, called additive color, andthe behavior of paint or ink or dye or pigment mixtures, called subtractive color. This problem arises because theabsorption of light by material substances follows different rules from the perception of light by the eye.A second problem has been the failure to describe the very important effects of strong luminance (lightness)contrasts in the appearance of colors reflected from a surface (such as paints or inks) as opposed to colors of light;"colors" such as browns or ochres cannot appear in mixtures of light. Thus, a strong lightness contrast between amid-valued yellow paint and a surrounding bright white makes the yellow appear to be green or brown, while astrong brightness contrast between a rainbow and the surrounding sky makes the yellow in a rainbow appear to be afainter yellow, or white.A third problem has been the tendency to describe color effects holistically or categorically, for example as acontrast between "yellow" and "blue" conceived as generic colors, when most color effects are due to contrasts onthree relative attributes that define all colors:1. lightness (light vs. dark, or white vs. black),2. saturation (intense vs. dull), and3. hue (e.g., red, orange, yellow, green, blue or purple).Thus, the visual impact of "yellow" vs. "blue" hues in visual design depends on the relative lightness and intensity ofthe hues.These confusions are partly historical, and arose in scientific uncertainty about color perception that was not resolveduntil the late 19th century, when the artistic notions were already entrenched. However, they also arise from theattempt to describe the highly contextual and flexible behavior of color perception in terms of abstract colorsensations that can be generated equivalently by any visual media.Many historical "color theorists" have assumed that three "pure" primary colors can mix all possible colors, and that any failure of specific paints or inks to match this ideal performance is due to the impurity or imperfection of the

Color theory 17

colorants. In reality, only imaginary "primary colors" used in colorimetry can "mix" or quantify all visible(perceptually possible) colors; but to do this, these imaginary primaries are defined as lying outside the range ofvisible colors; i.e., they cannot be seen. Any three real "primary" colors of light, paint or ink can mix only a limitedrange of colors, called a gamut, which is always smaller (contains fewer colors) than the full range of colors humanscan perceive.

Historical backgroundColor theory was originally formulated in terms of three "primary" or "primitive" colors—red, yellow and blue(RYB)—because these colors were believed capable of mixing all other colors. This color mixing behavior had longbeen known to printers, dyers and painters, but these trades preferred pure pigments to primary color mixtures,because the mixtures were too dull (unsaturated).

Goethe's color wheel from his 1810 Theory ofColours

The RYB primary colors became the foundation of 18th centurytheories of color vision, as the fundamental sensory qualities that areblended in the perception of all physical colors and equally in thephysical mixture of pigments or dyes. These theories were enhanced by18th-century investigations of a variety of purely psychological coloreffects, in particular the contrast between "complementary" oropposing hues that are produced by color afterimages and in thecontrasting shadows in colored light. These ideas and many personalcolor observations were summarized in two founding documents incolor theory: the Theory of Colours (1810) by the German poet andgovernment minister Johann Wolfgang von Goethe, and The Law ofSimultaneous Color Contrast (1839) by the French industrial chemistMichel Eugène Chevreul.

Subsequently, German and English scientists established in the late19th century that color perception is best described in terms of a different set of primary colors—red, green and blueviolet (RGB)—modeled through the additive mixture of three monochromatic lights. Subsequent research anchoredthese primary colors in the differing responses to light by three types of color receptors or cones in the retina(trichromacy). On this basis the quantitative description of color mixture or colorimetry developed in the early 20thcentury, along with a series of increasingly sophisticated models of color space and color perception, such as theopponent process theory.

Across the same period, industrial chemistry radically expanded the color range of lightfast synthetic pigments,allowing for substantially improved saturation in color mixtures of dyes, paints and inks. It also created the dyes andchemical processes necessary for color photography. As a result three-color printing became aesthetically andeconomically feasible in mass printed media, and the artists' color theory was adapted to primary colors mosteffective in inks or photographic dyes: cyan, magenta, and yellow (CMY). (In printing, dark colors are supplementedby a black ink, known as the CMYK system; in both printing and photography, white is provided by the color of thepaper.) These CMY primary colors were reconciled with the RGB primaries, and subtractive color mixing withadditive color mixing, by defining the CMY primaries as substances that absorbed only one of the retinal primarycolors: cyan absorbs only red (−R+G+B), magenta only green (+R−G+B), and yellow only blue violet (+R+G−B). Itis important to add that the CMYK, or process, color printing is meant as an economical way of producing a widerange of colors for printing, but is deficient in reproducing certain colors, notably orange and slightly deficient inreproducing purples. A wider range of color can be obtained with the addition of other colors to the printing process,such as in Pantone's Hexachrome printing ink system (six colors), among others.

Color theory 18

Munsell's color system represented as athree-dimensional solid showing all three colormaking attributes: lightness, saturation and hue.

For much of the 19th century artistic color theory either lagged behindscientific understanding or was augmented by science books writtenfor the lay public, in particular Modern Chromatics (1879) by theAmerican physicist Ogden Rood, and early color atlases developed byAlbert Munsell (Munsell Book of Color, 1915, see Munsell colorsystem) and Wilhelm Ostwald (Color Atlas, 1919). Major advanceswere made in the early 20th century by artists teaching or associatedwith the German Bauhaus, in particular Wassily Kandinsky, JohannesItten, Faber Birren and Josef Albers, whose writings mix speculationwith an empirical or demonstration-based study of color designprinciples.

Contemporary color theory must address the expanded range of mediacreated by digital media and print management systems, whichsubstantially expand the range of imaging systems and viewingcontexts in which color can be used. These applications are areas ofintensive research, much of it proprietary; artistic color theory has little to say about these complex newopportunities.

Traditional color theory

Complementary colors

Chevreul's 1855 "chromatic diagram" based on the RYB color model, showingcomplementary colors and other relationships

For the mixing of colored light, Newton’scolor wheel is often used to describecomplementary colors, which are colorswhich cancel each other's hue to produce anachromatic (white, gray or black) lightmixture. Newton offered as a conjecture thatcolors exactly opposite one another on thehue circle cancel out each other's hue; thisconcept was demonstrated more thoroughlyin the 19th century.

A key assumption in Newton's hue circlewas that the "fiery" or maximum saturatedhues are located on the outer circumferenceof the circle, while achromatic white is atthe center. Then the saturation of themixture of two spectral hues was predictedby the straight line between them; themixture of three colors was predicted by the"center of gravity" or centroid of threetriangle points, and so on.

Color theory 19

Primary, secondary, and tertiary colors of theRYB color model

According to traditional color theory based on subtractive primarycolors and the RYB color model, which is derived from paint mixtures,yellow mixed with violet, orange mixed with blue, or red mixed withgreen produces an equivalent gray and are the painter's complementarycolors. These contrasts form the basis of Chevreul's law of colorcontrast: colors that appear together will be altered as if mixed with thecomplementary color of the other color. Thus, a piece of yellow fabricplaced on a blue background will appear tinted orange, because orangeis the complementary color to blue.

Unfortunately, the artists' primary colors are not the same ascomplementary colors defined by light mixtures. This discrepancybecomes important when color theory is applied across media. Digitalcolor management uses a hue circle defined around the additiveprimary colors (the RGB color model), as the colors in a computermonitor are additive mixtures of light, not subtractive mixtures of paints.

One reason the artist's primary colors even work at all is that the imperfect pigments being used have slopedabsorption curves, and thus change color with concentration. A pigment that is pure red at high concentrations canbehave more like magenta at low concentrations. This allows it to make purples that would otherwise be impossible.Likewise, a blue that is ultramarine at high concentrations appears cyan at low concentrations, allowing it to be usedto mix green. Chromium red pigments can appear orange, and then yellow, as the concentration is reduced. It is evenpossible to mix very low concentrations of the blue mentioned and the chromium red to get a greenish color. Thisworks much better with oil colors than it does with water colors and dyes.So the old primaries depend on sloped absorption curves and pigment leakages to work, while the new scientificallyderived ones depend solely on controlling the amount of absorption in certain parts of the spectrum.Another reason the correct primary colors were not used by early artists is that they were not available as durablepigments. Modern methods in chemistry were needed to produce them.

Warm vs. cool colorsThe distinction between warm and cool colors has been important since at least the late 18th century [1] . It isgenerally not remarked in modern color science or colorimetry in reference to painting, but is still used in designpractices today. The contrast, as traced by etymologies in the Oxford English Dictionary, seems related to theobserved contrast in landscape light, between the "warm" colors associated with daylight or sunset and the "cool"colors associated with a gray or overcast day. Warm colors are often said to be hues from red through yellow,browns and tans included; cool colors are often said to be the hues from blue green through blue violet, most graysincluded. There is historical disagreement about the colors that anchor the polarity, but 19th century sources put thepeak contrast between red orange and greenish blue.Color theory has ascribed perceptual and psychological effects to this contrast. Warm colors are said to advance orappear more active in a painting, while cool colors tend to recede; used in interior design or fashion, warm colors aresaid to arouse or stimulate the viewer, while cool colors calm and relax. Most of these effects, to the extent they arereal, can be attributed to the higher saturation and lighter value of warm pigments in contrast to cool pigments. Thus,brown is a dark, unsaturated warm color that few people think of as visually active or psychologically arousing.Compare the traditional warm–cool association of color with the color temperature of a theoretical radiating blackbody, where the association of color with temperature is reversed. For instance, the hottest stars radiate blue light(i.e., with shorter wavelength and higher frequency) and the coolest radiate red.

Color theory 20

The hottest radiating bodies (e.g. stars) have a "cool" color while the less hot bodies radiate with a "warm" color. (Image in mired scale.)

Achromatic colorsAny color that lacks strong chromatic content is said to be unsaturated, achromatic, or near neutral. Pure achromaticcolors include black, white and all grays; near neutrals include browns, tans, pastels and darker colors. Near neutralscan be of any hue or lightness.Neutrals are obtained by mixing pure colors with either white,black or grey, or by mixing two complementarycolors. In color theory, neutral colors are colors easily modified by adjacent more saturated colors and they appear totake on the hue complementary to the saturated color. Next to a bright red couch, a gray wall will appear distinctlygreenish.Black and white have long been known to combine well with almost any other colors; black increases the apparentsaturation or brightness of colors paired with it, and white shows off all hues to equal effect.

Tints and shadesWhen mixing colored light (additive color models), the achromatic mixture of spectrally balanced red, green andblue (RGB) is always white, not gray or black. When we mix colorants, such as the pigments in paint mixtures, acolor is produced which is always darker and lower in chroma, or saturation, than the parent colors. This moves themixed color toward a neutral color—a gray or near-black. Lights are made brighter or dimmer by adjusting theirbrightness, or energy level; in painting, lightness is adjusted through mixture with white, black or a color'scomplement.It is common among some painters to darken a paint color by adding black paint—producing colors calledshades—or lighten a color by adding white—producing colors called tints. However it is not always the best way forrepresentational painting, as an unfortunate result is for colors to also shift in hue. For instance, darkening a color byadding black can cause colors such as yellows, reds and oranges, to shift toward the greenish or bluish part of thespectrum. Lightening a color by adding white can cause a shift towards blue when mixed with reds and oranges.Another practice when darkening a color is to use its opposite, or complementary, color (e.g. purplish-red added toyellowish-green) in order to neutralize it without a shift in hue, and darken it if the additive color is darker than theparent color. When lightening a color this hue shift can be corrected with the addition of a small amount of anadjacent color to bring the hue of the mixture back in line with the parent color (e.g. adding a small amount oforange to a mixture of red and white will correct the tendency of this mixture to shift slightly towards the blue end ofthe spectrum).

Color theory 21

Split primary colorsIn painting and other visual arts, two-dimensional color wheels or three-dimensional color solids are used as tools toteach beginners the essential relationships between colors. The organization of colors in a particular color modeldepends on the purpose of that model: some models show relationships based on Human color perception, whereasothers are based on the color mixing properties of a particular medium such as a computer display or set of paints.This system is still popular among contemporary painters, as it is basically a simplified version of Newton'sgeometrical rule that colors closer together on the hue circle will produce more vibrant mixtures. However, with therange of contemporary paints available, many artists simply add more paints to their palette as desired for a varietyof practical reasons. For example, they may add a scarlet, purple and/or green paint to expand the mixable gamut;and they include one or more dark colors (especially "earth" colors such as yellow ochre or burnt sienna) simplybecause they are convenient to have premixed. Printers commonly augment a CYMK palette with spot (trademarkspecific) ink colors.

Color harmony and color meaningIt has been suggested that "Colors seen together to produce a pleasing affective response are said to be inharmony".[2] However, color harmony is a somewhat misleading notion in that responses to color can be influencedby a range of different factors including individual differences (age, gender, etc.); cultural and social differences; aswell as contextual, temporal and perceptual factors. The following conceptual model illustrates this approach to colorharmony:

Wherein color harmony is a function (f) of the interaction between color/s (Col 1, 2, 3, …, n) and the factors thatinfluence positive aesthetic response to color: individual differences (ID) such as age, gender, personality andaffective state; cultural experiences (CE), the prevailing context (CX) which includes setting and ambient lighting;intervening perceptual effects (P) and the effects of time (T) in terms of prevailing social trends.[3]

In addition, given that humans can perceive over 2.8 million different hues,[4] it has been suggested that the numberof possible color combinations is virtually infinite thereby implying that predictive color harmony formulae arefundamentally unsound.[5] Despite this, many color theorists have devised formulae, principles or guidelines forcolor combination with the aim being to predict or specify positive aesthetic response or 'color harmony'. Colorwheel models have often been used as a basis for color combination principles or guidelines and for definingrelationships between colors. Some theorists and artists believe juxtapositions of complementary color will producestrong contrast, a sense of visual tension as well as 'color harmony'; while others believe juxtapositions of analogouscolors will elicit positive aesthetic response. Color combination guidelines suggest that colors next to each other onthe color wheel model (analogous colors) tend to produce a single-hued or monochromatic color experience andsome theorists also refer to these as 'simple harmonies'. In addition, split complementary color schemes usuallydepict a range of analogous hues plus a key complementary color. A triadic color scheme adopts any three colorsapproximately equidistant around a color wheel model. Feisner and Mahnke are among a number of authors whoprovide color combination guidelines in greater detail.[6] [7]

Color combination formulae and principles may provide some guidance but have limited practical application. Thisis because of the influence of contextual, perceptual and temporal factors which will influence how color/s areperceived in any given situation, setting or context. Such formulae and principles may be useful in fashion, interiorand graphic design, but much depends on the tastes, lifestyle and cultural norms of the viewer or consumer.As early as the ancient Greek philosophers, many theorists have devised color associations and linked particular connotative meanings to specific colors. However, connotative color associations and color symbolism tends to be culture-bound and may also vary across different contexts and circumstances. For example, red has many different connotative and symbolic meanings from exciting, arousing, sensual, romantic and feminine; to a symbol of good

Color theory 22

luck; and also acts as a signal of danger. Such color associations tend to be learned and do not necessarily holdirrespective of individual and cultural differences or contextual, temporal or perceptual factors.[8] It is important tonote that while color symbolism and color associations exist, their existence does not provide evidential support forcolor psychology or claims that color has therapeutic properties.[9]

Current statusColor theory has not developed an explicit explanation of how specific media affect color appearance: colors havealways been defined in the abstract, and whether the colors were inks or paints, oils or watercolors, transparencies orreflecting prints, computer displays or movie theaters, was not considered especially relevant. Josef Albersinvestigated the effects of relative contrast and color saturation on the illusion of transparency, but this is anexception to the rule.[10]

References[1] "color temperature" (http:/ / www. handprint. com/ HP/ WCL/ color12. html). handprint. 2009-04-19. . Retrieved 2011-06-09.[2] Burchett, K. E. (2002). Color harmony. Color Research and Application, 27 (1), pp28-31.[3] O'Connor, Z. (2010). Color harmony revisited. Color Research and Application, 35 (4), pp267-273.[4] Pointer, M. R. & Attridge, G.G. (1998). The number of discernible colors. Color Research and Application, 23 (1), pp52-54.[5] Hard, A. & Sivik, L. (2001). A theory of colors in combination - A descriptive model related to the NCS color-order system. Color Research

and Application, 26 (1), pp4-28.[6] Feisner, E. A. (2000). Colour: How to use colour in art and design. London: Laurence King.[7] Mahnke, F. (1996). Color, environment and human response. New York: John Wiley & Sons.[8] Bellantoni, Patti (2005). If it's Purple, Someone's Gonna Die. Elsevier, Focal Press. ISBN 0-240-80688-3.[9] O'Connor, Z. (2010). Colour psychology and colour therapy: Caveat emptor. Color Research and Application, (Published online in

'EarlyView' in advance of print).[10] Albers, Josef (2006). Interaction of Color. Revised and Expanded Edition. Yale University Press. ISBN 0-300-11595-4.

External links• Color Theory Tutorial by Worqx (http:/ / www. worqx. com/ color/ )• Handprint.com : Color (http:/ / handprint. com/ HP/ WCL/ wcolor. html) - a comprehensive site about color

perception, color psychology, color theory, and color mixing• Color Theory in Landscape Design (http:/ / landscaping. about. com/ od/ flowersherbsgroundcover1/ a/

flower_photos. htm)• The Dimensions of Colour (http:/ / www. huevaluechroma. com/ ) - color theory for artists using digital/

traditional media• Color Thesaurus (http:/ / www. hpl. hp. com/ personal/ Nathan_Moroney/ color-thesaurus. html) World's Largest

Database of Color Names• Stanford University CS 178 interactive Flash demo (http:/ / graphics. stanford. edu/ courses/ cs178/ applets/ locus.

html) introducing trichromatic color theory.

Additive color 23

Additive color

Additive color mixing: adding red to green yieldsyellow; adding all three primary colors together

yields white.

A rendered model, showing red, green and bluelights combining.

An additive color model involves light emitted directly from a sourceor illuminant of some sort. The additive reproduction process usuallyuses red, green and blue light to produce the other colors. Combiningone of these additive primary colors with another in equal amountsproduces the additive secondary colors cyan, magenta, and yellow.Combining all three primary lights (colors) in equal intensitiesproduces white. Varying the luminosity of each light (color) eventuallyreveals the full gamut of those three lights (colors).

Computer monitors and televisions are the most common form ofadditive light. The colored pixels do not overlap on the screen, butwhen viewed from a sufficient distance, the light from the pixelsdiffuses to overlap on the retina. Another common use of additive lightis the projected light used in theatrical lighting, such as plays, concerts,circus shows, and night clubs.[1]

Results obtained when mixing additive colors are oftencounterintuitive for people accustomed to the more everydaysubtractive color system of pigments, dyes, inks and other substanceswhich present color to the eye by reflection rather than emission. Forexample, in subtractive color systems green is a combination of yellowand blue; in additive color, red + green = yellow and no simplecombination will yield green. Additive color is a result of the way theeye detects color, and is not a property of light. There is a vastdifference between yellow light, with a wavelength of approximately580 nm, and a mixture of red and green light. However, both stimulateour eyes in a similar manner, so we do not detect that difference. (seeeye (cytology), color vision.)

The first permanent color photograph, taken byJames Clerk Maxwell in 1861.

James Clerk Maxwell is credited as being the father of additivecolor.[2] He had the photographer Thomas Sutton photograph a tartanribbon on black-and-white film three times, first with a red, then green,then blue color filter over the lens. The three black-and-white imageswere developed and then projected onto a screen with three differentprojectors, each equipped with the corresponding red, green, or bluecolor filter used to take its image. When brought into alignment, thethree images (a black-and-red image, a black-and-green image and ablack-and-blue image) formed a full color image, thus demonstratingthe principles of additive color.[3]

The following flowchart demonstrates an example of the process, stepby step.

Additive color 24

James Clerk Maxwell with his color top that heused for investigation of color vision and additive

color

Light source Medium wavelengths, or green, and long wavelengths, or red, radiate from two different projectors.

Projection screen Both the medium and long wavelengths reflect off of a spot on the screen.

Retina The medium and long wavelengths activate M and L cones on a spot on the retina.

Brain The brain interprets the equal amounts of medium and long signal as yellow.

To fully understand the process, it should be demonstrated how dull colors are obtained using cyan, magenta, andyellow instead of red, green, and blue.

Light source Cyan, or SM, and yellow, or ML, radiate from two different projectors.

Projectionscreen

Both the SM and ML reflect off of a spot on the screen.

Retina Some short, lots of medium, and some long wavelengths activate cones on a spot on the retina.

Brain The brain receives signals from the cones about some short, lots of medium, and some long wavelengths. It interprets the signalas light green.If the background is not black, it interprets the signal as dull green.

References[1] David Briggs (2007). "The Dimensions of Color" (http:/ / www. huevaluechroma. com/ 044. php). . Retrieved 2011-11-23.[2] "James Clerk Maxwell" (http:/ / www. cis. rit. edu/ node/ 280). Inventor's Hall of Fame, Rochester Institute of Technology Center for

Imaging Science. .[3] Robert Hirsch (2004). Exploring Colour Photography: A Complete Guide (http:/ / books. google. com/ books?id=4Gx2WItWGYoC&

pg=PA28& dq=maxwell+ additive+ color+ photograph+ register#PPA28,M1). Laurence King Publishing. ISBN 1-85669-420-8. .

External links• http:/ / www. edinphoto. org. uk/ 1_P/ 1_photographers_maxwell. htm (http:/ / www. edinphoto. org. uk/ 1_P/

1_photographers_maxwell. htm) - Photos and stories from the James Clerk Maxwell Foundation.• Stanford University CS 178 interactive Flash demo (http:/ / graphics. stanford. edu/ courses/ cs178/ applets/

colormixing. html) comparing additive and subtractive color mixing.

Subtractive color 25

Subtractive color

Subtractive color mixing

An 1877 color photo by Louis Ducos du Hauron, aFrench pioneer of color photography. The overlapping,

subtractive yellow, cyan and red (magenta) imageelements can clearly be seen.

A subtractive color model explains the mixing of paints, dyes,inks, and natural colorants to create a full range of colors, eachcaused by subtracting (that is, absorbing) some wavelengths oflight and reflecting the others. The color that a surface displaysdepends on which colors of the electromagnetic spectrum arereflected by it and therefore made visible.

Subtractive color systems start with light, presumably white light.Colored inks, paints, or filters between the viewer and the lightsource or reflective surface subtract wavelengths from the light,giving it color. If the incident light is other than white, our visualmechanisms are able to compensate well, but not perfectly, oftengiving a flawed impression of the "true" color of the surface.

Conversely, additive color systems start without light (black).Light sources of various wavelengths combine to make a color. Ineither type of system, three primary colors are combined tostimulate humans’ trichromatic color vision, sensed by the threetypes of cone cells in the eye, giving an apparently full range.

Wavelength absorption

The following flowchart illustrates an example of the process, stepby step.

Lightsource

S M L White light radiates from the light source.

↓ ↓ ↓

Cyan ink S M — Cyan ink absorbs long wavelengths, allowing the rest to pass through.

Yellow ink — M L Yellow ink absorbs short wavelengths, allowing the rest to pass through. The only wavelengths remaining are medium,which are green.

↓

Paper S M L The medium wavelengths reflect off the paper.

↓

Yellow ink — M L The medium wavelengths pass back through the yellow ink.

Cyan ink S M — The medium wavelengths pass back through the cyan ink.

↓

Subtractive color 26

Retina S M L The medium wavelengths activate the M cones in the retina.

↓

Brain S M L The brain interprets the signal from the M cones as green.

In order to fully understand the process, it should be demonstrated how black is obtained using red, green, and blue.

Lightsource

S M L White light radiates from the light source.

↓ ↓ ↓

Green ink — M — Green ink absorbs short and long wavelengths, allowing medium wavelengths to pass through.

↓

Red ink — — L Red ink absorbs short and medium wavelengths, allowing long wavelengths to pass through. However, there are no longwavelengths remaining to pass through, and all of the light has been absorbed.

RYB

Standard RYB Color Wheel

RYB (Red, Yellow, Blue) is the formerly standard set of subtractiveprimary colors used for mixing pigments. It is used in art and arteducation, particularly in painting. It predated modern scientific colortheory.

Red, yellow, and blue are the primary colors of the standard color"wheel". The secondary colors, violet (or purple), orange, and green(VOG) make up another triad, formed by mixing equal amounts of redand blue, red and yellow, and blue and yellow, respectively.

The RYB primary colors became the foundation of 18th centurytheories of color vision as the fundamental sensory qualities blended inthe perception of all physical colors and equally in the physical mixtureof pigments or dyes. These theories were enhanced by 18th-centuryinvestigations of a variety of purely psychological color effects, in

particular the contrast between "complementary" or opposing hues produced by color afterimages and in thecontrasting shadows in colored light. These ideas and many personal color observations were summarized in twofounding documents in color theory: the Theory of Colors (1810) by the German poet and government ministerJohann Wolfgang von Goethe, and The Law of Simultaneous Color Contrast (1839) by the French industrial chemistMichel-Eugène Chevreul.

CMYK printing processIn most color printing, the primary ink colors used are cyan, magenta, and yellow. Cyan is the complement of red,meaning that cyan acts like a filter that absorbs red. The amount of cyan applied to a paper will control how muchred will show. Magenta is the complement of green, and yellow the complement of blue. Combinations of differentamounts of the three inks can produce a wide range of colors; this is how artwork reproductions are mass-produced,although an under-toning of black ink is usually used as well. This mixture is called CMYK.

Subtractive color 27

References• Berns, Roy S. (2000). Billmeyer and Saltzman's Principles of Color Technology, 3rd edition. Wiley, New York.

ISBN 0-471-19459-X.• Stroebel, Leslie, John Compton, Ira Current, and Richard Zakia (2000). Basic Photographic Materials and

Processes, 2nd edition. Focal Press, Boston. ISBN 0-240-80405-8.• Wyszecki, Günther and W. S. Stiles (1982). Colour Science: Concept and Methods, Quantitative Data and

Formulae. Wiley, New York. ISBN 0-471-02106-7.

External links• Stanford University CS 178 interactive Flash demo [1] comparing additive and subtractive color mixing.

References[1] http:/ / graphics. stanford. edu/ courses/ cs178/ applets/ colormixing. html

28

Mixing Color

Color mixing

White light split by a prism. The additive primarycolors are clearly visible.

There are two types of color mixing: Additive and Subtractive. In bothcases there are three primary colors, three secondary colors (colorsmade from 2 of the three primary colors in equal amounts), and onetertiary color made from all three primary colors.

A simulated example of additive color mixing

Additive Mixing

Additive mixing of colors generally involves mixing colors of light. Inadditive mixing of colors there are three primary colors: red, green, andblue. In the absence of color or, when no colors are showing, the resultis black. If all three primary colors are showing, the result is white.When red and green combine, the result is yellow. When red and bluecombine, the result is magenta. Additive mixing is used in televisionand computer monitors to produce a wide range of colors using onlythree primary colors.

A simulated example of subtractive color mixing

Subtractive Mixing

Subtractive mixing is done by selectively removing certain colors, forinstance with optical filters. The three primary colors in subtractivemixing are yellow, magenta, and cyan. In subtractive mixing of color,the absence of color is white and the presence of all three primarycolors is black. In subtractive mixing of colors, the secondary colorsare the same as the primary colors from additive mixing, and viceversa. Subtractive mixing is used to create a variety of colors whenprinting on paper by combining a small number of ink colors, and alsowhen painting. The mixing of pigments does not produce perfectsubtractive color mixing because some light from the subtracted coloris still being reflected. This results in a darker and desaturated colorcompared to the color that would be achieved with ideal filters.

Color mixing 29

Importance to visionAdditive color mixing—red and green combining to make yellow, for example, or blue and yellow producingwhite—runs counter to the commonsense observation that, for example, yellow paint plus cyan paint makes greenpaint. In this case, one must understand that the wavelengths of light that reach the eye are often selected via thesemore intuitive subtractive processes: for example, cyan paint appears to our eye as cyan because it absorbs redwavelengths, and a yellow paint appears yellow because it absorbs blue wavelengths. When white light falls on acombination of cyan and yellow, then, both red and blue are absorbed, and green is reflected to the eye.[1]

External links• Interactive Java applet on the additive mixing of RGB colors [2] by Wolfgang Bauer• Interactive Java applet on the subtractive mixing of CYM colors [3] by Wolfgang Bauer

References• Macaulay, David and Neil Ardley (1988). The New Way Things Work. London: Dorling Kindersley Ltd. ISBN

0395938473.[1] "Sensory Reception: Human Vision: Structure and Function of the Eye" Encyclopaedia Britannica, vol. 27 1987[2] http:/ / chair. pa. msu. edu/ applets/ RGBColor/ a. htm[3] http:/ / chair. pa. msu. edu/ applets/ CYMColor/ a. htm

Primary color

The emission spectra of the three phosphors that define the additive primary colors of aCRT color video display. Unlike subtractive systems that mix red, yellow, and blue

paints, or magenta, yellow, and cyan inks, additive systems such as computer displaysmix red, green, and blue light to make all colors.

Primary colors are sets of colors thatcan be combined to make a usefulrange of colors. For humanapplications, three primary colors areusually used, since human color visionis trichromatic.

For additive combination of colors, asin overlapping projected lights or inCRT displays, the primary colorsnormally used are red, green, and blue.For subtractive combination of colors,as in mixing of pigments or dyes, suchas in printing, the primaries normallyused are cyan, magenta, and yellow,[1]

though the set of red, yellow, blue ispopular among artists.[2] See RGBcolor model, CMYK color model, andRYB color model for more on these popular sets of primary colors.

Any choice of primary colors is essentially arbitrary; for example, an early color photographic process, autochrome,typically used orange, green, and violet primaries.[3] However, unless negative amounts of a color are allowed thegamut will be restricted by the choice of primaries.

The combination of any two primary colors creates a secondary color.

Primary color 30

The most commonly used additive color primaries are the secondary colors of the most commonly used subtractivecolor primaries, and vice versa.

Biological basisPrimary colors are not a fundamental property of light but are often related to the physiological response of the eyeto light. Fundamentally, light is a continuous spectrum of the wavelengths that can be detected by the human eye, aninfinite-dimensional stimulus space.[4] However, the human eye normally contains only three types of colorreceptors, called cone cells. Each color receptor responds to different ranges of the color spectrum. Humans andother species with three such types of color receptors are known as trichromats. These species respond to the lightstimulus via a three-dimensional sensation, which generally can be modeled as a mixture of three primary colors.[4]

Before the nature of colorimetry and visual physiology were well understood, scientists such as Thomas Young,James Clark Maxwell, and Hermann von Helmholtz expressed various opinions about what should be the threeprimary colors to describe the three primary color sensations of the eye.[5] Young originally proposed red, green, andviolet, and Maxwell changed violet to blue; Helmholtz proposed "a slightly purplish red, a vegetation-green, slightlyyellowish (wave-length about 5600 tenth-metres), and an ultramarine-blue (about 4820)".[6] In modernunderstanding, the human cone cells do not correspond to any real primary colors.Species with different numbers of receptor cell types would have color vision requiring a different number ofprimaries. For example, for species known as tetrachromats, with four different color receptors, one would use fourprimary colors. Since humans can only see to 380 nanometers (violet), but tetrachromats can see into the ultravioletto about 300 nanometers, this fourth primary color for tetrachromats is located in the shorter-wavelength range.[7]

Many birds and marsupials are tetrachromats, and it has been suggested that some human females are tetrachromatsas well,[8] [9] having an extra variant version of the long-wave (L) cone type.[10] The peak response of human colorreceptors varies, even among individuals with "normal" color vision;[11] in non-human species this polymorphicvariation is even greater, and it may well be adaptive.[12] Most mammals other than primates have only two types ofcolor receptors and are therefore dichromats; to them, there are only two primary colors.It would be incorrect to assume that the world "looks tinted" to an animal (or human) with anything other than thehuman standard of three color receptors. To an animal (or human) born that way, the world would look normal to it,but the animal's ability to detect and discriminate colors would be different from that of a human with normal colorvision. If a human and an animal both look at a natural color, they see it as natural; however, if both look at a colorreproduced via primary colors, such as on a color television screen, the human may see it as matching the naturalcolor, while the animal does not, since the primary colors have been chosen to suit human capabilities.

Primary color 31

Additive primaries

Additive color mixing

The sRGB color triangle

Media that combine emitted lights to create the sensation of a range ofcolors are using the additive color system. Typically, the primarycolors used are red, green, and blue.[13]

Television and other computer and video displays are a commonexample of the use of additive primaries and the RGB color model.The exact colors chosen for the primaries are a technologicalcompromise between the available phosphors (including considerationssuch as cost and power usage) and the need for large color triangle toallow a large gamut of colors. The ITU-R BT.709-5/sRGB primariesare typical.

CIE 1931 RGB color triangle withmonochromatic primaries

Additive mixing of red and green light produces shades of yellow,orange, or brown.[14] Mixing green and blue produces shades of cyan,and mixing red and blue produces shades of purple, including magenta.Mixing nominally equal proportions of the additive primaries results inshades of grey or white; the color space that is generated is called anRGB color space.

The CIE 1931 color space defines monochromatic primary colors withwavelengths of 435.8 nm (violet), 546.1 nm (green) and 700 nm (red).The corners of the color triangle are therefore on the spectral locus, andthe triangle is about as big as it can be. No real display device usessuch primaries, as the extreme wavelengths used for violet and redresult in a very low luminous efficiency.

Primary color 32

Subtractive primariesMedia that use reflected light and colorants to produce colors are using the subtractive color method of color mixing.

TraditionalRYB (red, yellow, and blue) is a historical set of subtractive primary colors. It is primarily used in art and arteducation, particularly painting.[15] It predates modern scientific color theory.

RYB color wheel

RYB make up the primary colors in a painter's color wheel; thesecondary colors VOG (violet, orange, and green) make up anothertriad. Triads are formed by 3 equidistant colors on a particular colorwheel; neither RYB nor VOG is equidistant on a perceptually uniformcolor wheel, but rather have been defined to be equidistant in the RYBwheel.[16]

Painters have long used more than three "primary" colors in theirpalettes—and at one point considered red, yellow, blue, and green tobe the four primaries.[17] Red, yellow, blue, and green are still widelyconsidered the four psychological primary colors,[18] though red,yellow, and blue are sometimes listed as the three psychologicalprimaries,[19] with black and white occasionally added as a fourth andfifth.[20]

During the 18th century, as theorists became aware of Isaac Newton’s scientific experiments with light and prisms,red, yellow, and blue became the canonical primary colors—supposedly the fundamental sensory qualities that areblended in the perception of all physical colors and equally in the physical mixture of pigments or dyes. This theorybecame dogma, despite abundant evidence that red, yellow, and blue primaries cannot mix all other colors, and hassurvived in color theory to the present day.[21]

Using red, yellow, and blue as primaries yields a relatively small gamut, in which, among other problems, colorfulgreens, cyans, and magentas are impossible to mix, because red, yellow, and blue are not well-spaced around aperceptually uniform color wheel. For this reason, modern three- or four-color printing processes, as well as colorphotography, use cyan, yellow, and magenta as primaries instead.[22] Most painters include colors in their paletteswhich cannot be mixed from yellow, red, and blue paints, and thus do not fit within the RYB color model. Some whodo use a three-color palette opt for the more evenly spaced cyan, yellow, and magenta used by printers, and otherspaint with 6 or more colors to widen their gamuts.[23] The cyan, magenta, and yellow used in printing are sometimesknown as "process blue," "process red," and "process yellow."[24]

Primary color 33

CMYK color model, or four-color printingIn the printing industry, to produce the varying colors the subtractive primaries cyan, magenta, and yellow areapplied together in varying amounts. Before the color names cyan and magenta were in common use, these primarieswere often known as blue-green and purple, or in some circles as blue and red, respectively, and their exact color haschanged over time with access to new pigments and technologies.[25]

Subtractive color mixing – the magenta and cyanprimaries are sometimes called purple and

blue-green, or red and blue

Mixing yellow and cyan produces green colors; mixing yellow withmagenta produces reds, and mixing magenta with cyan produces blues.In theory, mixing equal amounts of all three pigments should producegrey, resulting in black when all three are applied in sufficient density,but in practice they tend to produce muddy brown colors. For thisreason, and to save ink and decrease drying times, a fourth pigment,black, is often used in addition to cyan, magenta, and yellow.

The resulting model is the so-called CMYK color model. Theabbreviation stands for cyan, magenta, yellow, and key—black isreferred to as the key color, a shorthand for the key printing plate thatimpressed the artistic detail of an image, usually in black ink.[26]

In practice, colorant mixtures in actual materials such as paint tend tobe more complex. Brighter or more saturated colors can be createdusing natural pigments instead of mixing, and natural properties of

pigments can interfere with the mixing. For example, mixing magenta and green in acrylic creates a darkcyan—something which would not happen if the mixing process were perfectly subtractive.

In the subtractive model, adding white to a color, whether by using less colorant or by mixing in a reflective whitepigment such as zinc oxide, does not change the color’s hue but does reduce its saturation. Subtractive color printingworks best when the surface or paper is white, or close to it.A system of subtractive color does not have a simple chromaticity gamut analogous to the RGB color triangle, but agamut that must be described in three dimensions. There are many ways to visualize such models, using various 2Dchromaticity spaces or in 3D color spaces.[27]

Psychological primaries

Approximations within the sRGB gamut to the “aim colors” of theNatural Color System, a model based on the opponent process

theory of color vision.

Main article: Opponent process. See also: NaturalColor System, Unique hues

The opponent process is a color theory that states that thehuman visual system interprets information about colorby processing signals from cones and rods in anantagonistic manner. The three types of cones have someoverlap in the wavelengths of light to which they respond,so it is more efficient for the visual system to recorddifferences between the responses of cones, rather thaneach type of cone's individual response. The opponentcolor theory suggests that there are three opponentchannels: red versus green, blue versus yellow, and blackversus white.[28] Responses to one color of an opponentchannel are antagonistic to those of the other color. The

Primary color 34

particular colors considered by an observer to be uniquely representative of the concepts red, yellow, green, blue,white, and black might be called “psychological primary colors”, because any other color can be described in termsof some combination of these.

Notes and references[1] Matthew Luckiesh (1915). Color and Its Applications (http:/ / books. google. com/ ?id=0BgCAAAAYAAJ& pg=RA1-PA221&

dq=magenta+ cyan+ yellow+ date:0-1923+ printing). D. Van Nostrand company. pp. 58, 221. .[2] Chris Grimley and Mimi Love (2007). Color, space, and style: all the details interior designers need to know but can never find (http:/ /

books. google. com/ ?id=uVxa-_N4LQ4C& pg=PA137& dq=ryb+ color+ model+ paint& q=ryb color model paint). Rockport Publishers.p. 137. ISBN 9781592532278. .

[3] Walter Hines Page and Arthur Wilson Page (1908). The World's Work: Volume XV: A History of Our Time (http:/ / books. google. com/?id=hKPvxXgBN1oC& pg=PA9508& dq=autochrome+ orange+ violet+ green). Doubleday, Page & Company. .

[4] Michael I. Sobel (1989). Light (http:/ / books. google. com/ ?id=PDmAdQpmxl8C& pg=PA58& dq=spectrum+ color+ infinite-dimensional+cones). University of Chicago Press. pp. 52–62. ISBN 0226767515. .

[5] Edward Albert Sharpey-Schäfer (1900). Text-book of physiology (http:/ / books. google. com/ ?id=fz0uAAAAYAAJ& pg=PA1107&dq=primary+ red-green-and-violet+ maxwell+ sensation). 2. Y. J. Pentland. p. 1107. .

[6] Alfred Daniell (1904). A text book of the principles of physics (http:/ / books. google. com/ ?id=oPQZAAAAYAAJ& pg=PA575&dq=primary+ red-green-and-violet+ maxwell). Macmillan and Co. p. 575. .

[7] Goldsmith, Timothy H. "What Birds See" Scientific American July 2006—Article about the tetrachromatic vision of birds: "What Birds See"in PDF format: (http:/ / www. csulb. edu/ web/ labs/ bcl/ elab/ avian vision_intro. pdf)

[8] Backhaus, Kliegl & Werner "Color vision, perspectives from different disciplines" (De Gruyter, 1998), pp.115–116, section 5.5.[9] Pr. Mollon (Cambridge university), Pr. Jordan (Newcastle university) "Study of women heterozygote for colour difficiency" (Vision

Research, 1993)[10] M. Neitz, T. W. Kraft, and J. Neitz (1998). "Expression of L cone pigment gene subtypes in females". Vision Research 38 (21): 3221–3225.

doi:10.1016/S0042-6989(98)00076-5. PMID 9893829.[11] Neitz, Jay & Jacobs, Gerald H. (1986). "Polymorphism of the long-wavelength cone in normal human colour vision." (http:/ / www. nature.

com/ nature/ journal/ v323/ n6089/ abs/ 323623a0. html) Nature. 323, 623–625.[12] Jacobs, Gerald H. (1996). "Primate photopigments and primate color vision." (http:/ / www. pubmedcentral. nih. gov/ articlerender.

fcgi?artid=40094) PNAS. 93 (2), 577–581.[13] Thomas D. Rossing and Christopher J. Chiaverina (1999). Light science: physics and the visual arts (http:/ / books. google. com/

?id=jpH1_dCT_UcC& pg=PA178& dq=red+ green+ blue+ additive+ color+ primaries+ violet). Birkhäuser. p. 178. ISBN 9780387988276. .[14] "Some Experiments on Color", Nature 111, 1871, in John William Strutt (Lord Rayleigh) (1899). Scientific Papers (http:/ / books. google.

com/ ?id=KWMSAAAAIAAJ& pg=PA84& dq=date:0-1923+ light+ red+ green+ yellow-or-orange). University Press. .[15] Tom Fraser and Adam Banks (2004). Designer’s Color Manual: The Complete Guide to Color Theory and Application (http:/ / books.

google. com/ ?id=WXZNPaX-LvcC& pg=PA27& dq=red-yellow-blue+ color+ mixing). Chronicle Books. ISBN 081184210X. .[16] Stephen Quiller (2002). Color Choices (http:/ / books. google. com/ ?id=jiUTZQj_v5QC& pg=PA12& dq=what-is-a-color-wheel+ spaced+

red+ yellow+ blue). Watson–Guptill. ISBN 0823006972. .[17] For instance Leonardo da Vinci wrote of these four simple colors in his notebook circa 1500. See Rolf Kuenhi. “Development of the Idea of

Simple Colors in the 16th and Early 17th Centuries”. Color Research and Application. Volume 32, Number 2, April 2007.[18] Resultby Leslie D. Stroebel, Ira B. Current (2000). Basic Photographic Materials and Processes (http:/ / books. google. com/

?id=BRYa6Qpsw48C& pg=PP1& dq=Basic+ Photographic+ Materials+ and+ Processes). Focal Press. ISBN 0240803450. .[19] MS Sharon Ross , Elise Kinkead (2004). Decorative Painting & Faux Finishes (http:/ / books. google. com/ ?id=DPJUWRydR9kC&

dq=red+ yellow+ blue+ paint-mixing+ + subtractive). Creative Homeowner. ISBN 1580111793. .[20] Swirnoff, Lois (2003). Dimensional Color (http:/ / books. google. com/ ?id=sG5MqtZuFF0C& dq="psychological+ primaries"+ blue+

-green). W. W. Norton & Company. ISBN 0393731022. .[21] Bruce MacEvoy. “Do ‘Primary’ Colors Exist?” ( Material Trichromacy section (http:/ / www. handprint. com/ HP/ WCL/ color6.

html#materialtrichromacy)). Handprint. Accessed 10 August 2007.[22] “Development of the Idea of Simple Colors in the 16th and Early 17th Centuries”. Color Research and Application. Volume 32, Number 2,

April 2007.[23] Bruce MacEvoy. “ Secondary Palette (http:/ / www. handprint. com/ HP/ WCL/ palette4e. html).” Handprint. Accessed 14 August 2007. For

general discussion see Bruce MacEvoy. “Mixing With a Color Wheel” ( Saturation Costs section (http:/ / www. handprint. com/ HP/ WCL/color14. html#satcost)). Handprint. Accessed 14 August 2007.

[24] Cheap Brochure Printing – Process Blue / Process Red / Process Yellow / Process Black (http:/ / www. printoutlet. us/ glossary.php?glossaryid=2526)

[25] Ervin Sidney Ferry (1921). General Physics and Its Application to Industry and Everyday Life (http:/ / books. google. com/?id=3rYXAAAAIAAJ& pg=PA621& dq=date:0-1923+ additive+ color+ mixing+ primary). John Wiley & Sons. .

Primary color 35

[26] Frank S. Henry (1917). Printing for School and Shop: A Textbook for Printers' Apprentices, Continuation Classes, and for General use inSchools (http:/ / books. google. com/ ?id=UAAvAAAAMAAJ& pg=PA292& dq=black+ date:0-1923+ key-plate+ printing+ color). JohnWiley & Sons. .

[27] See the google image results (http:/ / images. google. com/ images?q=cmyk gamut) for “cmyk gamut” for examples.[28] Michael Foster (1891). A Text-book of physiology (http:/ / books. google. com/ ?id=Swn8ztLFTdkC& pg=RA1-PA921& dq=hering+

red-green+ yellow-blue+ young-helmholtz+ date:0-1923). Lea Bros. & Co. p. 921. .

External links• Bruce MacEvoy. "Do Primary Colors Exist?" (http:/ / www. handprint. com/ HP/ WCL/ color6. html).

handprint.com. The history and science of primary colors, part of MacEvoy’s sprawling comprehensive site aboutcolor.

• Ask A Scientist: Primary Colors (http:/ / www. newton. dep. anl. gov/ askasci/ phy00/ phy00871. htm)• The Color-Sensitive Cones at HyperPhysics (http:/ / hyperphysics. phy-astr. gsu. edu/ hbase/ vision/ colcon.

html#c1)• Color Tutorial (http:/ / www. tomjewett. com/ colors/ index. html)

Colorfulness

Original image, with relatively muted colors

L*C*h (CIELAB) chroma increased 50%

HSL saturation increased 50%; notice that changing HSL saturation also affects the perceived lightness of a color

Colorfulness 36

CIELAB lightness preserved, with a* and b* stripped, to make a grayscale image

In colorimetry and color theory, colorfulness, chroma, and saturation are related but distinct concepts referring tothe perceived intensity of a specific color. Colorfulness is the degree of difference between a color and gray. Chromais the colorfulness relative to the brightness of another color that appears white under similar viewing conditions.Saturation is the colorfulness of a color relative to its own brightness.[1] Though this general concept is intuitive,terms such as chroma, saturation, purity, and intensity are often used without great precision, and even whenwell-defined depend greatly on the specific color model in use.A highly colorful stimulus is vivid and intense, while a less colorful stimulus appears more muted, closer to gray.With no colorfulness at all, a color is a “neutral” gray (an image with no colorfulness in any of its colors is calledgrayscale). With three attributes—colorfulness (or chroma or saturation), lightness (or brightness), and hue—anycolor can be described.

Saturation

Scale ofsaturation (0%at bottom andits black and

white).

Saturation is one of three coordinates in the HSL and HSV color spaces. Note that virtually allcomputer software implementing these spaces use a very rough approximation to calculate thevalue they call "saturation", such as the formula described for HSV and this value has little, ifanything, to do with the description shown here.

The saturation of a color is determined by a combination of light intensity and how much it isdistributed across the spectrum of different wavelengths. The purest (most saturated) color isachieved by using just one wavelength at a high intensity, such as in laser light. If the intensitydrops, then as a result the saturation drops. To desaturate a color of given intensity in a subtractivesystem (such as watercolor), one can add white, black, gray, or the hue's complement.

Various correlates of saturation follow.CIELUV

The chroma normalized by the lightness:

where (u′n, v′n) is the chromaticity of the white point, and chroma is defined below.[2]

By analogy, in CIELAB this would yield:

The CIE has not formally recommended this equation since CIELAB has no chromaticity diagram, and thisdefinition therefore lacks direct correlation with older concepts of saturation.[3] Nevertheless, this equation providesa reasonable predictor of saturation, and demonstrates that adjusting the lightness in CIELAB while holding (a*, b*)fixed does affect the saturation.

Colorfulness 37

But the following formula is in agreement with the human perception of saturation: The formula proposed by EvaLübbe is in agreement with the verbal definition of Manfred Richter: Saturation is the proportion of pure chromaticcolor in the total color sensation.[4]

where Sab is the saturation, L* the lightness and C*ab is the chroma of the color.CIECAM02

The square root of the colorfulness divided by the brightness:

This definition is inspired by experimental work done with the intention of remedying CIECAM97s's poorperformance.[5] [6] M is proportional to the chroma C (M = CFL

0.25), thus the CIECAM02 definition bears somesimilarity to the CIELUV definition. An important difference is that the CIECAM02 model accounts for the viewingconditions through the parameter FL.[5]

Excitation purity

Excitation purity is the relative distance from the white point. Contours ofconstant purity can be found by shrinking the spectral locus about the white point.The points along the line segment have the same hue, with pe increasing from 0 to1 between the white point and position on the spectral locus (position of the color

on the horseshoe shape in the diagram) or (as at the saturated end of the line shownin the diagram) position on the line of purples.

The excitation purity (purity for short) of astimulus is its difference from theilluminant's white point relative to thefurthest point on the chromaticity diagramwith the same hue (dominant wavelength formonochromatic sources); using the CIE1931 color space:[7]

Colorfulness 38

where (xn, yn) is the chromaticity of the white point and (xI, yI) is the point on the perimeter whose line segment tothe white point contains the chromaticity of the stimulus. Different color spaces, such as CIELAB or CIELUV maybe used, and will yield different results.

Chroma in CIE 1976 L*a*b* and L*u*v* color spacesThe naïve definition of saturation does not specify its response function. In the CIE XYZ and RGB color spaces, thesaturation is defined in terms of additive color mixing, and has the property of being proportional to any scalingcentered at white or the white point illuminant. However, both color spaces are nonlinear in terms of psychovisuallyperceived color differences. It is also possible, and sometimes desirable to define a saturation-like quantity that islinearized in term of the psychovisual perception.In the CIE 1976 L*a*b* and L*u*v* color spaces, the unnormalized chroma is the radial component of thecylindrical coordinate CIE L*C*h (lightness, chroma, hue) representation of the L*a*b* and L*u*v* color spaces,also denoted as CIE L*C*h(a*b*) or CIE L*C*h for short, and CIE L*C*h(u*v*). The transformation of (a*, b*) to(C*ab, hab) is given by:

and analogously for CIE L*C*h(u*v*).The chroma in the CIE L*C*h(a*b*) and CIE L*C*h(u*v*) coordinates has the advantage of being morepsychovisually linear, yet they are non-linear in terms of linear component color mixing. And therefore, chroma inCIE 1976 L*a*b* and L*u*v* color spaces is very much different from the traditional sense of "saturation".

Chroma in color appearance modelsAnother, psychovisually even more accurate, but also more complex method to obtain or specify the saturation is touse the color appearance model, like CIECAM. The chroma component of the LCh (lightness, chroma, hue)coordinate, and becomes a function of parameters like the chrominance and physical brightness of the illumination,or the characteristics of the emitting/reflecting surface, which is also psychovisually more sensible.

References[1] Mark D. Fairchild. “ Color Appearance Models: CIECAM02 and Beyond (http:/ / www. cis. rit. edu/ fairchild/ PDFs/ AppearanceLec. pdf)”.

Slides from a tutorial at the IS&T/SID 12th Color Imaging Conference. 9 November 2004. Retrieved 19 September 2007.[2] Schanda, János (2007). Colorimetry: Understanding the CIE System (http:/ / books. google. com/ ?id=g8VDAgAACAAJ&

dq=intitle:Colorimetry+ intitle:Understanding+ intitle:the+ intitle:CIE+ intitle:System). Wiley Interscience. ISBN 978-0-470-04904-4. , page88.

[3] Hunt, Robert William Gainer (1993). Leslie D. Stroebel, Richard D. Zakia. ed. The Focal Encyclopedia of Photography (http:/ / books.google. com/ ?id=CU7-2ZLGFpYC& pg=PA124& dq="correlate+ of+ saturation"+ cielab+ chroma+ lightness+ chromaticity). Focal Press.p. 124. ISBN 0240514173. .

[4] Lübbe, Eva (2010). Colours in the Mind - Colour Systems in Reality- A formula for colour saturation. [Book on Demand].ISBN 978-3-7881-4057-1.

[5] Moroney, Nathan; Fairchild, Mark D.; Hunt, Robert W.G.; Li, Changjun; Luo, M. Ronnier; Newman, Todd (November 12 2002). "TheCIECAM02 Color Appearance Model" (http:/ / www. polybytes. com/ misc/ Meet_CIECAM02. pdf) (PDF). IS&T/SID Tenth Color ImagingConference. Scottsdale, Arizona: The Society for Imaging Science and Technology. ISBN 0-89208-241-0. .

[6] Juan, Lu-Yin G.; Luo, Ming R. (June 2002). "Magnitude estimation for scaling saturation" (http:/ / spiedl. aip. org/ getabs/ servlet/GetabsServlet?prog=normal& id=PSISDG004421000001000575000001& idtype=cvips& gifs=yes). In Robert Chung, Allan Rodrigues.Proceedings of SPIE. 4421. 9th Congress of the International Colour Association. pp. 575–578. doi:10.1117/12.464511. .

[7] Stroebel, Leslie D.; Zakia, Richard D. (1993). The Focal Encyclopedia of Photography (http:/ / books. google. com/ ?id=CU7-2ZLGFpYC&pg=PA121& dq="excitation+ purity") (3E ed.). Focal Press. p. 121. ISBN 0240514173. .

Dichromatism 39

DichromatismDichromatism (or polychromatism) is a phenomenon where the hue of the colour in materials or solutions aredependent on both the concentration of the absorbing substance and the depth or thickness of the mediumtraversed.[1] In most substances which are not dichromatic, only the brightness and saturation of the colour dependon their concentration and layer thickness.Examples of dichromatic substances are pumpkin seed oil, bromophenol blue and resazurin. When the layer ofpumpkin seed oil is less than 0.7 mm thick, the oil appears bright green, and in layer thicker than this, it appearsbright red.The phenomenon is related to both the physical chemistry properties of the substance and the physiological responseof the human visual system to colour. This combined physicochemical–physiological basis was first explained in2007.[2]

Physical explanationDichromatic properties can be explained by the Beer-Lambert law and by the excitation characteristics of the threetypes of cone photoreceptors in the human retina. Dichromatism is potentially observable in any substance that hasan absorption spectrum with one wide but shallow local minimum and one narrow but deep local minimum. Theapparent width of the deep minimum may also be limited by the end of the visible range of human eye; in this case,the true full width may not necessarily be narrow. As the thickness of the substance increases, the perceived huechanges from that defined by the position of the wide-but-shallow minimum (in thin layers) to the hue of thedeep-but-narrow minimum (in thick layers).The absorbance spectrum of pumpkin seed oil has the wide-but-shallow minimum in the green region of thespectrum and deep local minimum in the red region. In thin layers, the absorption at any specific green wavelength isnot as low as it is for the red minimum, but a broader band of greenish wavelengths are transmitted, and hence theoverall appearance is green. The effect is enhanced by the greater sensitivity to green of the photoreceptors in thehuman eye, and the narrowing of the red transmittance band by the long-wavelength limit of cone photoreceptorsensitivity. According to the Beer-Lambert law, when viewing through the coloured substance (and thus ignoringreflection), the proportion of light transmitted at a given wavelength, T, decreases exponentially with thickness t, T =e-at, where a is the absorbance at that wavelength. Let Ge-aGt be the green transmittance and Re-aRt be the redtransmittance. The ratio of the two transmitted intensities is then (G/R)e(aR-aG)t. If the red absorbance is less than thegreen, then as the thickness t increases, so does the ratio of red to green transmitted light, which causes the apparenthue of the colour to switch from green to red.

Dichromatism 40

QuantificationThe extent of dichromatism of material can be quantified by the Kreft's dichromaticity index (DI). It is defined as thedifference in hue angle (Δhab) between the colour of the sample at the dilution, where the chroma (colour saturation)is maximal and the colour of four times more diluted (or thinner) and four times more concentrated (or thicker)sample. The two hue angle differences are called dichromaticity index towards lighter (Kreft's DIL) anddichromaticity index towards darker (Kreft's DID) respectively.[3] Kreft's dichromaticity index DIL and DID forpumpkin oil, which is one of the most dichromatic substances, are −9 and −44, respectively. This means thatpumpkin oil changes its colour from green-yellow to orange-red (for 44 degrees in Lab colour space) when thethickness of the observed layer is increased from cca 0.5 mm to 2 mm; and it changes slightly towards green (for 9degrees) if its thickness is reduced for 4-fold.

HistoryA record by William Herschel (1738–1822), shows he observed dichromatism with a solution of ferrous sulphate in1801 when working on an early solar telescope, but he did not recognise the effect.[4]

References[1] Kennard IG, Howell DH (1941) Types of colouring in minerals. Am Mineral 26:405–421[2] Kreft S and Kreft M (2007) Physicochemical and physiological basis of dichromatic colour, Naturwissenschaften 94, 935-939. On-line PDF

(http:/ / www. springerlink. com/ content/ h5630lr536pj1333/ fulltext. pdf)[3] Kreft S, Kreft M. (2009). "Quantification of dichromatism: a characteristic of color in transparent materials" (http:/ / www. opticsinfobase.

org/ josaa/ abstract. cfm?URI=josaa-26-7-1576). Journal of the Optical Society of America A 26 (7): 1576–1581.Bibcode 2009JOSAA..26.1576K. doi:10.1364/JOSAA.26.001576. .

[4] The History of the Telescope - By Henry C. King - Page 141 (http:/ / books. google. com/ books?id=KAWwzHlDVksC& lpg=PA136&dq=Lilienthal telescope& pg=PA141#v=onepage& q& f=false)

Hue 41

Hue

Hue in the HSB/HSL encodings of RGB

An image with the hues cyclically shifted in HSLspace

The hues in the image of this PaintedBunting are cyclically rotated with

time.

Hue is one of the main properties of acolor, defined technically (in theCIECAM02 model), as "the degree towhich a stimulus can be described assimilar to or different from stimuli thatare described as red, green, blue, andyellow,"[1] (the unique hues). Theother main correlatives of colorappearance are colorfulness, chroma,saturation, lightness, and brightness.

Usually, colors with the same hue aredistinguished with adjectives referringto their lightness and/or chroma, suchas with "light blue", "pastel blue","vivid blue". Exceptions includebrown, which is a dark orange,[2] andpink, a light red with reduced chroma.

In painting color theory, a hue refers toa pure color—one without tint or shade(added white or black pigment,respectively).[3] A hue is an element ofthe color wheel. Hues are firstprocessed in the brain in areas in theextended V4 called globs.[4] [5]

Computing hue

In opponent color spaces in which twoof the axes are perceptually orthogonalto lightness, such as the CIE 1976 (L*,a*, b*) (CIELAB) and 1976 (L*, u*,v*) (CIELUV) color spaces, hue maybe computed together with chroma byconverting these coordinates fromrectangular form to polar form. Hue is the angular component of the polar representation, while chroma is the radialcomponent.

Specifically, in CIELAB:[6]

while, analogously, in CIELUV:[6]

Where, atan2 is a two-argument inverse tangent.

Hue 42

Computing hue from RGBPreucil[7] describes a color hexagon, similar to a trilinear plot described by Evans, Hanson, and Brewer,[8] whichmay be used to compute hue from RGB. To place red at 0°, green at 120°, and blue at 240°.

Note: This is equation assumes the form atan2(x,y), many programs and spreadsheets use atan2(y,x).Equivalently, one may solve:

Preucil used a polar plot, which he termed a color circle.[7] Using R, G, and B, one may compute hue angle using thefollowing scheme: determine which of the six possible orderings of R, G, and B prevail, then apply the formulagiven in the table below.

HSV color space as a conical object

An illustration of the relationship between the"hue" of colors with maximal saturation in HSV

and HSL with their corresponding RGBcoordinates.

Ordering Hue Region Formula

Red-Yellow

Yellow-Green

Green-Cyan

Cyan-Blue

Blue-Magenta

Magenta-Red

Note that in each case the formula contains the fraction , where H is the highest of R, G, and B; L is the

lowest, and M is the mid one between the other two. This is referred to as the Preucil Hue Error, and was used in thecomputation of mask strength in photomechanical color reproduction.[9]

Hue angles computed for the Preucil circle agree with the hue angle computed for the Preucil Hexagon at integermultiples of 30 degrees (red, yellow, green, cyan, blue, magenta, and the colors mid-way between contiguous pairs)and differ by approximately 1.2 degrees at odd integer multiples of 15 degrees (based on the circle formula), themaximum divergence between the two.

Hue 43

The process of converting an RGB color into an HSL color space or HSV color space is usually based on a 6-piecepiecewise mapping, treating the HSV cone as a hexacone, or the HSL double cone as a double hexacone.[10] Theformulae used are those in the table above.

Specialized huesThe hues exhibited by caramel colorings and beers are fairly limited in range. The Linner hue index is used toquantify the hue of such products.

Hue as a qualification in the names of artist's colorsManufacturers of pigments use the word hue e.g. 'Cadmium Yellow (hue)' to indicate that the original pigmentationingredient, often toxic, has been replaced by safer (or cheaper) alternatives whilst retaining the hue of the original.Replacements are often used for chromium, cadmium and alizarin.

Hue vs. dominant wavelengthDominant wavelength (or sometimes equivalent wavelength) is a physical analog to the perceptual attribute hue. Ona chromaticity diagram, a line is drawn from a white point through the coordinates of the color in question, until itintersects the spectral locus. The wavelength at which the line intersects the spectrum locus is identified as the color'sdominant wavelength if the point is on the same side of the white point as the spectral locus, and as the color'scomplementary wavelength if the point is on the opposite side.[11]

Hue difference: or ?There are two main ways in which hue difference is quantified. The first is the simple difference between the twohue angles. The symbol for this expression of hue difference is in CIELAB and in CIELUV. Theother is computed as the residual total color difference after Lightness and Chroma differences have been accountedfor; its symbol is in CIELAB and in CIELUV.

References[1] Mark Fairchild, "Color Appearance Models: CIECAM02 and Beyond." Tutorial slides for IS&T/SID 12th Color Imaging Conference.[2] C J Bartleson, "Brown". Color Research and Application, 1 : 4, p 181-191 (1976).[3] "The Color Wheel and Color Theory" (http:/ / creativecurio. com/ 2008/ 05/ the-color-wheel-and-color-theory/ ). Creative Curio. 2008-05-16.

. Retrieved 2011-06-09.[4] Conway, BR; Moeller, S; Tsao, DY. (2007). "Specialized color modules in macaque extrastriate cortex". Neuron 56 (3): 560–73.

doi:10.1016/j.neuron.2007.10.008. PMID 17988638.[5] Conway, BR; Tsao, DY (2009). "Color-tuned neurons are spatially clustered according to color preference within alert macaque posterior

inferior temporal cortex.". Proceedings of the National Academy of Sciences of the United States of America 106 (42): 18034–9.doi:10.1073/pnas.0810943106. PMC 2764907. PMID 19805195.

[6] Colorimetry, second edition: CIE Publication 15.2. Vienna: Bureau Central of the CIE, 1986.[7] Frank Preucil, "Color Hue and Ink Transfer … Their Relation to Perfect Reproduction, TAGA Proceedings, p 102-110 (1953).[8] Ralph Merrill Evans, W T Hanson, and W Lyle Brewer, Principles of Color Photography. New York: Wiley, 1953[9] Miles Southworth, Color Separation Techniques, second edition. Livonia, New York: Graphic Arts Publishing, 1979[10] Max K. Agoston (2004). Computer Graphics and Geometric Modelling v. 1: Implementation and Algorithms (http:/ / books. google. com/

?id=fGX8yC-4vXUC& pg=PA301& lpg=PA301& dq=hsv+ + hue+ rgb#PPA304,M1). Springer. pp. 301–304. ISBN 1852338180. .[11] Deane B Judd and Günter Wyszecki, Color in Business, Science, and Industry. New York: Wiley, 1976.

Hue 44

External links• Editing of hue in photography (http:/ / gimps. de/ en/ tutorials/ gimp/ picture-photo-image/ improve-colors/ )

Tints and shades“Tint” redirects here. For other uses, see tint (disambiguation)

Some shades of blue

In color theory, a tint is the mixture of a color with white, whichincreases lightness, and a shade is the mixture of a color with black,which reduces lightness. Mixing a color with any neutral color,including black and white, reduces the chroma, or colorfulness, whilethe hue remains unchanged.

When mixing colored light (additive color models), the achromaticmixture of spectrally balanced red, green and blue (RGB) is alwayswhite, not gray or black. When we mix colorants, such as the pigmentsin paint mixtures, a color is produced which is always darker and lowerin chroma, or saturation, than the parent colors. This moves the mixedcolor toward a neutral color—a gray or near-black. Lights are madebrighter or dimmer by adjusting their brightness, or energy level; inpainting, lightness is adjusted through mixture with white, black or acolor's complement.

It is common among some artistic painters to darken a paint color by adding black paint—producing colors calledshades—or to lighten a color by adding white—producing colors called tints. However, this is not always the bestway for representational painting, since an unfortunate result is for colors to also shift in their hues. For instance,darkening a color by adding black can cause colors such as yellows, reds and oranges, to shift toward the greenish orbluish part of the spectrum. Lightening a color by adding white can cause a shift towards blue when mixed with redsand oranges. Another practice when darkening a color is to use its opposite, or complementary, color (e.g.purplish-red added to yellowish-green) in order to neutralize it without a shift in hue, and darken it if the additivecolor is darker than the parent color. When lightening a color this hue shift can be corrected with the addition of asmall amount of an adjacent color to bring the hue of the mixture back in line with the parent color (e.g. adding asmall amount of orange to a mixture of red and white will correct the tendency of this mixture to shift slightlytowards the blue end of the spectrum).

Tints and shades 45

An extension of the color wheel: the color sphere. Colors nearest the center or the poles are most achromatic. Colors of the same lightness andsaturation are of the same nuance. Colors of the same hue and saturation, but of different lightness, are said to be tints and shades. Colors of the same

hue and lightness, but of varying saturation, are called tones.

Lightness 46

Lightness

Three hues in the Munsell color model. Eachcolor differs in value from top to bottom in equalperception steps. The right column undergoes a

dramatic change in perceived color.

Lightness (sometimes called value or tone) is a property of a color, or adimension of a color space, that is defined in a way to reflect thesubjective brightness perception of a color for humans along alightness–darkness axis. A color's lightness also corresponds to itsamplitude.

Various color models have an explicit term for this property. TheMunsell color model uses the term value, while the HSL color modeland Lab color space use the term lightness. The HSV model uses theterm value a little differently: a color with a low value is nearly black,but one with a high value is the pure, fully saturated color.

In subtractive color (i.e. paints) value changes can be achieved byadding black or white to the color. However, this also reducessaturation. Chiaroscuro and Tenebrism both take advantage of dramaticcontrasts of value to heighten drama in art. Artists may also employshading, subtle manipulation of value.

Relationship between lightness, value, andluminance

The Munsell value has long been used as a perceptually uniformlightness scale. A question of interest is the relationship between theMunsell value scale and the relative luminance. Aware of theWeber–Fechner law, Munsell remarked "Should we use a logarithmiccurve or curve of squares?"[1] Neither option turned out to be quitecorrect; scientists eventually converged on a roughly cube-root curve,consistent with the Stevens power law for brightness perception,reflecting the fact that lightness is proportional to the number of nerve impulses per nerve fiber per unit time.[2] Theremainder of this section is a chronology of lightness approximations, leading to CIELAB.

Note: Munsell's V runs from 0 to 10, while Y typically runs from 0 to 100 (often interpreted as a percent). Typically,the relative luminance is normalized so that the "reference white" (say, magnesium oxide) has a tristimulus value ofY=100. Since the reflectance of magnesium oxide (MgO) relative to the perfect reflecting diffuser is 97.5%, V=10corresponds to Y=100/97.5%≈102.6 if MgO is used as the reference.[3]

Lightness 47

Observe that the lightness is 50% for a luminance of around 18% relative to the referencewhite.

1920Priest et al. provide a basicestimate of the Munsell value(with Y running from 0 to 1 inthis case):[4]

1933Munsell, Sloan, and Godlovelaunch a study on the Munsellneutral value scale, consideringseveral proposals relating therelative luminance to theMunsell value, and suggest:[5] [6]

1943Newhall, Nickerson, and Judd prepare a report for the Optical Society of America. They suggest a quinticparabola (relating the reflectance in terms of the value):[7]

1943Using Table II of the O.S.A. report, Moon and Spencer express the value in terms of the luminance:[8]

1944Saunderson and Milner introduce a subtractive constant in the previous expression, for a better fit to theMunsell value.[9] Later, Jameson and Hurvich claim that this corrects for simultaneous contrast effects.[10] [11]

1955Ladd and Pinney of Eastman Kodak are interested in the Munsell value as a perceptually uniform lightnessscale for use in television. After considering one logarithmic and five power-law functions (per Stevens' powerlaw), they relate value to reflectance by raising the reflectance to the power of 0.352:[12]

Realizing this is quite close to the cube root, they simplify it to:

1958Glasser et al. define the lightness as ten times the Munsell value (so that the lightness ranges from 0 to100):[13]

1964

Lightness 48

Wyszecki simplifies this to:[14]

This formula approximates the Munsell value function for (it is not applicable for Y<1%)and is used for the CIE 1964 color space.

1976CIELAB uses the following formula:

where is the Y tristimulus value of a "specified white object" and is subject to the restriction. Pauli removes this restriction by computing a linear extrapolation which maps Y/Yn=0 to

L*=0 and is tangent to the formula above at the point at which the linear extension takes effect. First, thetransition point is determined to be , then the slope of is computed. This gives the two-part function:[15]

The lightness is then .At first glance, you might approximate the lightness function by a cube root, an approximation that is found in muchof the technical literature. However, the linear segment near black is significant. The best-fit pure power function hasan exponent of about 0.42, far from 1/3.An 18% grey card, having a reflectance of 0.18, has lightness very close to 50. It is called "mid grey" because itslightness is midway between black and white.

References[1] Kuehni, Rolf G. (February 2002). "The early development of the Munsell system". Color Research & Application 27 (1): 20–27.

doi:10.1002/col.10002.[2] Hunt, Robert W. G. (May 18 1957). "Light Energy and Brightness Sensation". Nature 179 (4568): 1026. doi:10.1038/1791026a0.[3] Valberg, Arne (2006). Light Vision Color (http:/ / books. google. com/ ?id=hNDS1C6x0WYC& pg=PA200& dq=0. 975+ OR+ 97. 5+

"magnesium+ oxide"). John Wiley and Sons. p. 200. ISBN 0470849029. .[4] Priest, Irwin G.; Gibson, K.S.; McNicholas, H.J. (September 1920). An examination of the Munsell color system. I: Spectral and total

reflection and the Munsell scale of Value. Technical paper 167. United States Bureau of Standards. p. 27[5] Munsell, A.E.O.; Sloan, L.L.; Godlove, I.H. (November 1933). "Neutral value scales. I. Munsell neutral value scale" (http:/ / www.

opticsinfobase. org/ abstract. cfm?URI=josa-23-11-394). JOSA 23 (11): 394–411. doi:10.1364/JOSA.23.000394. . Note: This paper contains ahistorical survey stretching to 1760.

[6] Munsell, A.E.O.; Sloan, L.L.; Godlove, I.H. (December 1933). "Neutral value scales. II. A comparison of results and equations describingvalue scales" (http:/ / www. opticsinfobase. org/ abstract. cfm?URI=josa-23-12-419). JOSA 23 (12): 419–425. doi:10.1364/JOSA.23.000419. .

[7] Newhall, Sidney M.; Nickerson, Dorothy; Judd, Deane B (May 1943). "Final report of the O.S.A. subcommittee on the spacing of theMunsell colors" (http:/ / www. opticsinfobase. org/ abstract. cfm?URI=josa-33-7-385). Journal of the Optical Society of America 33 (7):385–418. doi:10.1364/JOSA.33.000385. .

[8] Moon, Parry; Spencer, Domina Eberle (May 1943). "Metric based on the composite color stimulus" (http:/ / www. opticsinfobase. org/abstract. cfm?URI=josa-33-5-270). JOSA 33 (5): 270–277. doi:10.1364/JOSA.33.000270. .

[9] Saunderson, Jason L.; Milner, B.I. (March 1944). "Further study of ω space" (http:/ / www. opticsinfobase. org/ abstract.cfm?URI=josa-34-3-167). JOSA 34 (3): 167–173. doi:10.1364/JOSA.34.000167. .

[10] Hurvich, Leo M.; Jameson, Dorothea (November 1957). "An Opponent-Process Theory of Color Vision" (http:/ / psycnet. apa. org/ index.cfm?fa=buy. optionToBuy& id=1959-02846-001). Psychological Review 64 (6): 384–404. doi:10.1037/h0041403. PMID 13505974. .

[11] Jameson, Dorothea; Leo M., Hurvich (May 1964). "Theory of brightness and color contrast in human vision". Vision Research 4 (1-2):135–154. doi:10.1016/0042-6989(64)90037-9. PMID 5888593.

[12] Ladd, J.H.; Pinney, J.E. (September 1955). "Empirical relationships with the Munsell Value scale" (http:/ / ieeexplore. ieee. org/ xpls/abs_all. jsp?isnumber=4055542& arnumber=4055558). Proceedings of the Institute of Radio Engineers 43 (9): 1137.doi:10.1109/JRPROC.1955.277892. .

Lightness 49

[13] Glasser, L.G.; A.H. McKinney, C.D. Reilly, and P.D. Schnelle (October 1958). "Cube-root color coordinate system" (http:/ / www.opticsinfobase. org/ abstract. cfm?URI=josa-48-10-736). JOSA 48 (10): 736–740. doi:10.1364/JOSA.48.000736. .

[14] Wyszecki, Günther (November 1963). "Proposal for a New Color-Difference Formula" (http:/ / www. opticsinfobase. org/ abstract.cfm?URI=josa-53-11-1314). JOSA 53 (11): 1318–1319. doi:10.1364/JOSA.53.001318. . Note: The asterisks are not used in the paper.

[15] Pauli, Hartmut K.A. (1976). "Proposed extension of the CIE recommendation on "Uniform color spaces, color spaces, and color-differenceequations, and metric color terms"" (http:/ / www. opticsinfobase. org/ abstract. cfm?URI=josa-66-8-866). JOSA 66 (8): 866–867.doi:10.1364/JOSA.66.000866. .

50

Perception of Color

Opponent process

Opponent colors based on experiment. Deuteranopes see littledifference between the two colors in the central column.

The color opponent process is a color theory that statesthat the human visual system interprets information aboutcolor by processing signals from cones and rods in anantagonistic manner. The three types of cones (L for long,M for medium and S for short) have some overlap in thewavelengths of light to which they respond, so it is moreefficient for the visual system to record differencesbetween the responses of cones, rather than each type ofcone's individual response. The opponent color theorysuggests that there are three opponent channels: redversus green, blue versus yellow, and black versus white(the latter type is achromatic and detects light-darkvariation, or luminance).[1] Responses to one color of anopponent channel are antagonistic to those to the othercolor. That is, opposite opponent colors are never perceived together – there is no "greenish red" or "yellowish blue".

While the trichromatic theory defines the way the retina of the eye allows the visual system to detect color with threetypes of cones, the opponent process theory accounts for mechanisms that receive and process information fromcones. Though the trichromatic and opponent processes theories were initially thought to be at odds, it later came tobe understood that the mechanisms responsible for the opponent process receive signals from the three types ofcones and process them at a more complex level.[2]

Besides the cones, which detect light entering the eye, the biological basis of the opponent theory involves two othertypes of cells: bipolar cells, and ganglion cells. Information from the cones is passed to the bipolar cells in the retina,which may be the cells in the opponent process that transform the information from cones. The information is thenpassed to ganglion cells, of which there are two major classes: magnocellular, or large-cell layers, and parvocellular,or small-cell layers. Parvocellular cells, or P cells, handle the majority of information about color, and fall into twogroups: one that processes information about differences between firing of L and M cones, and one that processesdifferences between S cones and a combined signal from both L and M cones. The first subtype of cells areresponsible for processing red–green differences,and the second process blue–yellow differences. P cells alsotransmit information about intensity of light (how much of it there is) due to their receptive fields.

Opponent process 51

HistoryJohann Wolfgang von Goethe first studied the physiological effect of opposed colors in his Theory of Colours in1810.[3] Goethe arranged his color wheel symmetrically, "for the colours diametrically opposed to each other in thisdiagram are those which reciprocally evoke each other in the eye. Thus, yellow demands purple; orange, blue; red,green; and vice versa: thus again all intermediate gradations reciprocally evoke each other."[4] [5]

Ewald Hering proposed opponent color theory in 1892.[6] He thought that the colors red, yellow, green, and blue arespecial in that any other color can be described as a mix of them, and that they exist in opposite pairs. That is, eitherred or green is perceived and never greenish-red; although yellow is a mixture of red and green in the RGB colortheory, the eye does not perceive it as such.In 1957, Hurvich and Jameson provided quantitative data for Hering's color opponency theory. Their method wascalled "hue cancellation". Hue cancellation experiments start with a color (e.g. yellow) and attempt to determine howmuch of the opponent color (e.g. blue) of one of the starting color's components must be added to eliminate any hintof that component from the starting color (Wolfe, Kluender, & Levi, 2009).[7]

Griggs expanded the concept to reflect a wide range of opponent processes for biological systems in this bookBiological Relativity (c) 1967.In 1970, Richard Solomon expanded Hurvich's general neurological opponent process model to explain emotion,drug addiction, and work motivation.[8] [9]

The opponent color theory can be applied to computer vision and implemented as the "Gaussian color model."[10]

Complementary-color afterimagesIf we stare at a red square for forty seconds, and immediately look at a white sheet of paper we'll often perceive agreen square on the blank sheet. This complementary color afterimage is more easily explained by the opponenttheory than the trichromatic; in the opponent-process theory, fatigue of pathways promoting red produce the illusionof a green square.[11]

Subjective color and new colors

Reddish green and yellowish blueUnder normal circumstances, there is no hue one could describe as a mixture of opponent hues; that is, as a huelooking "redgreen" or "yellowblue". However, in 1983 Crane and Piantanida[12] carried out an experiment underspecial viewing conditions in which red and green stripes (or blue and yellow stripes) were placed adjacent to eachother and the image held in the same position relative to the viewer's eyes (using an eye tracker to compensate forminor muscle movements). Under such conditions, the borders between the stripes seemed to disappear and thecolors flowed into each other, making it apparently possible to override the opponency mechanisms and, for amoment, get some people to perceive novel colors. :

"[s]ome observers indicated that although they were aware that what they were viewing was a color (that is,the field was not achromatic), they were unable to name or describe the color. One of these observers was anartist with a large color vocabulary. Other observers of the novel hues described the first stimulus as areddish-green."[13]

However, some subjects in the Crane and Piantanida study merely reported seeing hallucinatory textures, such as blue specks on a yellow backdrop. A possible explanation is that the study did not control for variations in the perceived luminance of the colors from subject to subject (two colors are equiluminant for an observer when rapidly alternating between the colors produces the least impression of flickering). To investigate this, Vincent Billock, Gerald Gleason and Brian Tsou set up a similar experiment which controlled for luminance.[14] They had the

Opponent process 52

following observation:"We found that when colors were equiluminant, subjects saw reddish greens, bluish yellows, or a multistablespatial color exchange (an entirely novel perceptual phenomena [sic]); when the colors werenonequiluminant, subjects saw spurious pattern formation."

This led them to propose a 'soft-wired model of cortical color opponency', in which populations of neurons competeto fire and in which the 'losing' neurons go completely silent. In this model, eliminating competition by, for instance,inhibiting connections between neural populations can allow mutually exclusive neurons to fire together.[14]

Other usesOpponent processes have also been used to explain pain, touch, facial expression of emotion,[15] smell, taste, andbalance.

References[1] Michael Foster (1891). A Text-book of physiology (http:/ / books. google. com/ ?id=Swn8ztLFTdkC& pg=RA1-PA921& dq=hering+

red-green+ yellow-blue+ young-helmholtz+ date:0-1923). Lea Bros. & Co. p. 921. .[2] Kandel ER, Schwartz JH and Jessell TM, 2000. Principles of Neural Science, 4th ed., McGraw–Hill, New York. pp. 577–80.[3] "Goethe's Color Theory" (http:/ / webexhibits. org/ colorart/ ch. html). Vision science and the emergence of modern art. .[4] Goethe, Johann (1810). Theory of Colours, paragraph #50.[5] "Goethe on Colours" (http:/ / books. google. com/ ?id=H7TlAAAAMAAJ& pg=RA1-PA121& dq="reciprocally+ evoke+ each+ other+ in+

the+ eye"#v=onepage& q="reciprocally evoke each other in the eye"& f=false). The Art-Union 2 (18): 107. July 15, 1840. .[6] Hering E, 1964. Outlines of a Theory of the Light Sense. Harvard University Press, Cambridge, Mass.[7] Hurvich, Leo M.; Jameson, Dorothea (November 1957). "An opponent-process theory of color vision". Psychological Review 64 (6, Part I):

384–404. doi:10.1037/h0041403. PMID 13505974.[8] Solomon, R.L. and Corbit, J.D. (1973). "An Opponent-Process Theory of Motivation: II. Cigarette Addiction". Journal of Abnormal

Psychology, 81 (2), pp. 158–171.[9] Solomon, R.L. and Corbit, J.D. (1974). "An Opponent-Process Theory of Motivation: I. Temporal Dynamics of Affect". Psychological

Review 81 (2), pp. 119–145.[10] Geusebroek, J.-M.; van den Boomgaard, R.; Smeulders, A.W.M.; Geerts, H. (December 2001). "Color invariance". Pattern Analysis and

Machine Intelligence, IEEE Transactions on 23 (12): 1338–1350. doi:10.1109/34.977559.[11] Griggs, R. A. (2009). "SENSATION AND PERCEPTION". Psychology: A Concise Introduction (2 ed.). Worth Publishers. p. 92.

ISBN 9781429200820. OCLC 213815202. " color information is processed at the post-receptor cell level (by bipolar, ganglion, thalamic, andcortical cells) according to the opponent-process theory."

[12] *Crane HD and Piantanida TP, 1983. On Seeing Reddish Green and Yellowish Blue. Science, 221:1078–80.[13] Suarez J; Suarez, Juan (2009). "Reddish Green: A Challenge for Modal Claims About Phenomenal Structure". Philosophy and

Phenomenological Research 78 (2): 346. doi:10.1111/j.1933-1592.2009.00247.x.[14] Billock, Vincent A.; Gerald A. Gleason, Brian H. Tsou (2001). "Perception of forbidden colors in retinally stabilized equiluminant images:

an indication of softwired cortical color opponency?" (http:/ / aris. ss. uci. edu/ ~kjameson/ BillockEtAlImpossibleColorsJOSA2001. pdf).Journal of the Optical Society of America A (Optical Society of America) 18 (10): 2398–2403. doi:10.1364/JOSAA.18.002398. . Retrieved2010-08-21.

[15] Susskind JM, Lee DH, Cusi A, Feiman R, Grabski W, Anderson AK, (2008). Expressing fear enhances sensory acquisition. NatureNeuroscience 11 (7):843–850. doi:10.1038/nn.2138 Link to Abstract (http:/ / www. nature. com/ neuro/ journal/ v11/ n7/ abs/ nn. 2138. html)

Opponent process 53

Further reading• Baccus SA, 2007. Timing and computation in inner retinal circuitry. Annu Rev Physiol, 69:271–90.• Masland RH, 2001. Neuronal diversity in the retina. Curr Opin Neurobiol, 11(4):431–6.• Masland RH, 2001. The fundamental plan of the retina. Nat Neurosci. 4(9):877–86.• Sowden PT and Schyns PG, 2006. Channel surfing in the visual brain. Trends Cogn Sci. 10(12):538–45.• Wässle H, 2004. Parallel processing in the mammalian retina. Nat Rev Neurosci, 5(10):747–57.

Impossible colorsReddish Green redirects here. Or see Reddish (an area of the Metropolitan Borough of Stockport, in GreaterManchester, England).

Impossible colors or forbidden colors are hues that cannot be perceived in ordinary viewing conditions from lightthat is a combination of various intensities of the various frequencies of visible light. Examples of impossible colorsare bluish-yellow and reddish-green.[1] This does not mean the muddy brown color created when mixing red andgreen paints, or the green color from mixing yellow and blue paints, but rather colors that appear to be similar to, forexample, both red and green, or both yellow and blue. Other colors never experienced in ordinary viewing, butperceivable under special artificial laboratory conditions, would also be termed impossible colors.

Where opposing colors cancel each other out, the remaining color on the verticalaxis is perceived. However, under special conditions, a mixture of opposing colors

can be seen without the remaining color interfering.

Opponent process

The color opponent process is a color theorythat states that the human visual systeminterprets information about color byprocessing signals from cones and rods in anantagonistic manner. The three types ofcones have some overlap in the wavelengthsof light to which they respond, so it is moreefficient for the visual system to recorddifferences between the responses of cones,rather than each type of cone's individualresponse. The opponent color theorysuggests that there are three opponentchannels: red versus green, blue versusyellow, and black versus white (the lattertype is achromatic and detects light-dark variation, or luminance). Responses to one color of an opponent channel areantagonistic to those to the other color.

Impossible colors 54

Claimed evidence for ability to see impossible colors

Some people may be able to see the color"yellow–blue" in this image. Allow your eyes to

cross until both + symbols are on top of eachother.

In 1983, Hewitt D. Crane and Thomas P. Piantanida carried out testsusing a device that had a field of a vertical red stripe adjacent to avertical green stripe (or in some cases, yellow–blue). In contrast toapparatus used in simpler tests the device had the ability to trackinvoluntary eye movement, and adjust mirrors so that the image wouldappear to be completely stable. The boundary of the red–green stripeswas stabilised on the retina of one eye while the other eye was patchedand the field outside the stripes was blanked with occluders. Thisallowed for a mixing of the two colors in the brain, producing neithergreen for a yellow–blue test, nor brown for a red green test, but newcolors entirely. Some of the volunteers for the experiment evenreported that afterwards, they could still imagine the new colors for a period of time.[1]

Other researchers dispute the existence of colors forbidden by opponency theory and claim they are, in reality,intermediate colors.[2] See also binocular rivalry.

Impossible colors in fictionIn 1927, American horror fiction author H. P. Lovecraft wrote a short story called "The Colour Out of Space" inwhich a meteorite crashed into a family farm in rural New England. The meteorite contained a mysterious globule ofa color that was "almost impossible to describe," with a note that it was "only by analogy" that professors studyingthe globule called it a color at all.David Lindsay in A Voyage to Arcturus described ulfire and jale, two colors visible under the sun Alppain: "Just asblue is delicate and mysterious, yellow clear and unsubtle, and red sanguine and passionate, so he felt ulfire to bewild and painful [and] jale [to be] dreamlike, feverish, and voluptuous."In 1955, the poet Robert Graves wrote "Welsh Incident," in which something unusual from the sea caves of Cricciethis described as "mostly nameless colours, colours you'd like to see."Octarine is Terry Pratchett's imaginary eighth color, described as a "greenish-yellow purple."A hoax or spoof recording by Negativland, featuring the fictional character Crosley Bendix, purports to describe thenewly discovered, "fourth primary" color, named "squant.""hTun" is an impossible color that is "similar to brown" in the book Fairest, by Gail Carson Levine.In episode 4 of the first series of Nebulous, "Holofile 333: Madness Is a Strange Colour", Vartox Paint Company'snew color, Garrow (a sort of yellowy black but with more of a pinky green feel...), is sending people insane.In "Resurection", the final episode of Futurama's sixth season, the Colorama segment ends with Fry accidentallycreating an entirely new color in a rainbow. Since the entire segment is in black & white, this new color appears asjust another shade of grey to the viewer.

Impossible colors 55

References[1] Hewitt D. Crane and Thomas P. Piantanida, "On Seeing Reddish Green and Yellowish Blue" (http:/ / www. jstor. org/ stable/ pdfplus/

1691544. pdf), Science, New Series, Vol.221, No. 4615 (Sep. 9, 1983), pp. 1078–1080[2] P.-J. Hsieh and P.U. Tse, "Illusory color mixing upon perceptual fading and filling-in does not result in ‘forbidden colors’" (http:/ / www.

sciencedirect. com/ science?_ob=GatewayURL& _method=citationSearch& _uoikey=B6T0W-4J8K5V6-2& _origin=SDEMFRHTML&_version=1& md5=465db58c44297db465517611f90a4cce), Vision Research, Vol.46, Issue 14, July 2006, Pages 2251–2258doi:10.1016/j.visres.2005.11.030.

• Billock, Vincent A., and Brian H. Tsou. "Seeing Forbidden Colors." Scientific American Feb. 2010: 72–77. Print.

Color vision

White light shone onto a green surface isperceived as green by the human eye, and

processed as such in the brain's visual cortex.

Colorless, green, and red photographic filters asimaged ("perceived") by digital camera

Color vision is the capacity of an organism or machine to distinguishobjects based on the wavelengths (or frequencies) of the light theyreflect, emit, or transmit. Colors can be measured and quantified invarious ways; indeed, a human's perception of colors is a subjectiveprocess whereby the brain responds to the stimuli that are producedwhen incoming light reacts with the several types of conephotoreceptors in the eye.

Wavelength and hue detection

Isaac Newton discovered that white light splits into its componentcolors when passed through a prism, but that if those bands of coloredlight pass through another and rejoin, they make a white beam. Thecharacteristic colors are, from low to high frequency: red, orange,yellow, green, cyan, blue, violet. Sufficient differences in frequencygive rise to a difference in perceived hue; the just noticeable differencein wavelength varies from about 1 nm in the blue-green and yellowwavelengths, to 10 nm and more in the red and blue. Though the eyecan distinguish up to a few hundred hues, when those pure spectralcolors are mixed together or diluted with white light, the number ofdistinguishable chromaticities can be quite high.

In very low light levels, vision is scotopic: light is detected by rod cellsof the retina. Rods are maximally sensitive to wavelengths near 500 nm, and play little, if any, role in color vision. Inbrighter light, such as daylight, vision is photopic: light is detected by cone cells which are responsible for colorvision. Cones are sensitive to a range of wavelengths, but are most sensitive to wavelengths near 555 nm. Betweenthese regions, mesopic vision comes into play and both rods and cones provide signals to the retinal ganglion cells.The shift in color perception from dim light to daylight gives rise to differences known as the Purkinje effect.

The perception of "white" is formed by the entire spectrum of visible light, or by mixing colors of just a fewwavelengths, such as red, green, and blue, or by mixing just a pair of complementary colors such as blue andyellow.[1]

Color vision 56

Physiology of color perception

Normalized response spectra of human cones, S, M, and L types, tomonochromatic spectral stimuli, with wavelength given in nanometers.

The same figures as above represented here as a single curve in three(normalized cone response) dimensions

Perception of color begins with specializedretinal cells containing pigments with differentspectral sensitivities, known as cone cells. Inhumans, there are three types of cones sensitiveto three different spectra, resulting intrichromatic color vision.

The cones are conventionally labeled accordingto the ordering of the wavelengths of the peaksof their spectral sensitivities: short (S), medium(M), and long (L) cone types. These three typesdo not correspond well to particular colors aswe know them. Rather, the perception of coloris achieved by a complex process that startswith the differential output of these cells in theretina and it will be finalized in the visualcortex and associative areas of the brain.

For example, while the L cones have beenreferred to simply as red receptors,microspectrophotometry has shown that theirpeak sensitivity is in the greenish-yellowregion of the spectrum. Similarly, the S- andM-cones do not directly correspond to blue andgreen, although they are often depicted as such.It is important to note that the RGB colormodel is merely a convenient means forrepresenting color, and is not directly based onthe types of cones in the human eye.

The peak response of human cone cells varies,even among individuals with 'normal' colorvision;[2] in non-human species thispolymorphic variation is even greater, and itmay well be adaptive.[3]

Theories of color vision

Two complementary theories of color vision are the trichromatic theory and the opponent process theory. Thetrichromatic theory, or Young–Helmholtz theory, proposed in the 19th century by Thomas Young and Hermann vonHelmholtz, as mentioned above, states that the retina's three types of cones are preferentially sensitive to blue, green,and red. Ewald Hering

Color vision 57

Relative brightness sensitivity of the human visual system as a function ofwavelength

proposed the opponent process theory in1872.[4] It states that the visual systeminterprets color in an antagonistic way: red vs.green, blue vs. yellow, black vs. white. Wenow know both theories to be correct,describing different stages in visualphysiology.[5]

Cone cells in the human eye

Cone type Name Range Peak wavelength[6]

[7]

S β 400–500 nm 420–440 nm

M γ 450–630 nm 534–555 nm

L ρ 500–700 nm 564–580 nm

A range of wavelengths of light stimulates each of these receptor types to varying degrees. Yellowish-green light, forexample, stimulates both L and M cones equally strongly, but only stimulates S-cones weakly. Red light, on theother hand, stimulates L cones much more than M cones, and S cones hardly at all; blue-green light stimulates Mcones more than L cones, and S cones a bit more strongly, and is also the peak stimulant for rod cells; and blue lightstimulates S cones more strongly than red or green light, but L and M cones more weakly. The brain combines theinformation from each type of receptor to give rise to different perceptions of different wavelengths of light.The opsins (photopigments) present in the L and M cones are encoded on the X chromosome; defective encoding ofthese leads to the two most common forms of color blindness. The OPN1LW gene, which codes for the opsin presentin the L cones, is highly polymorphic (a recent study by Verrelli and Tishkoff found 85 variants in a sample of 236men[8] ). A very small percentage of women may have an extra type of color receptor because they have differentalleles for the gene for the L opsin on each X chromosome. X chromosome inactivation means that only one opsin isexpressed in each cone cell, and some women may therefore show a degree of tetrachromatic color vision.[9]

Variations in OPN1MW, which codes the opsin expressed in M cones, appear to be rare, and the observed variantshave no effect on spectral sensitivity.

Color vision 58

Color in the human brain

Visual pathways in the human brain. The ventral stream (purple) is important incolor recognition. The dorsal stream (green) is also shown. They originate from a

common source in the visual cortex.

Color processing begins at a very early levelin the visual system (even within the retina)through initial color opponent mechanisms.Both Helmholtz's trichromatic theory, andHering's opponent process theory aretherefore correct, but trichromacy arises atthe level of the receptors, and opponentprocesses arise at the level of retinalganglion cells and beyond. In Hering'stheory opponent mechanisms refer to theopposing color effect of red–green,blue–yellow, and light–dark. However, inthe visual system, it is the activity of thedifferent receptor types that are opposed.Some midget retinal ganglion cells oppose Land M cone activity, which correspondsloosely to red–green opponency, butactually runs along an axis from blue-green to magenta. Small bistratified retinal ganglion cells oppose input fromthe S cones to input from the L and M cones. This is often thought to correspond to blue–yellow opponency, butactually runs along a color axis from lime green to violet.

Visual information is then sent to the brain from retinal ganglion cells via the optic nerve to the optic chiasma: apoint where the two optic nerves meet and information from the temporal (contralateral) visual field crosses to theother side of the brain. After the optic chiasma the visual tracts are referred to as the optic tracts, which enter thethalamus to synapse at the lateral geniculate nucleus (LGN).

The LGN is divided into laminae (zones), of which there three types: the M-laminae, consisting primarily of M-cells,the P-laminae, consisting primarily of P-cells, and the koniocellular laminae. M- and P-cells received relativelybalanced input from both L- and M-cones throughout most of the retina, although this seems to not be the case at thefovea, with midget cells synapsing in the P-laminae. The koniocellular laminae receive axons from the smallbistratified ganglion cells.[10] [11]

After synapsing at the LGN, the visual tract continues on back to the primary visual cortex (V1) located at the backof the brain within the occipital lobe. Within V1 there is a distinct band (striation). This is also referred to as "striatecortex", with other cortical visual regions referred to collectively as "extrastriate cortex". It is at this stage that colorprocessing becomes much more complicated.In V1 the simple three-color segregation begins to break down. Many cells in V1 respond to some parts of the spectrum better than others, but this "color tuning" is often different depending on the adaptation state of the visual system. A given cell that might respond best to long wavelength light if the light is relatively bright might then become responsive to all wavelengths if the stimulus is relatively dim. Because the color tuning of these cells is not stable, some believe that a different, relatively small, population of neurons in V1 is responsible for color vision. These specialized "color cells" often have receptive fields that can compute local cone ratios. Such "double-opponent" cells were initially described in the goldfish retina by Nigel Daw;[12] [13] their existence in primates was suggested by David H. Hubel and Torsten Wiesel and subsequently proven by Bevil Conway.[14] As Margaret Livingstone and David Hubel showed, double opponent cells are clustered within localized regions of V1 called blobs, and are thought to come in two flavors, red–green and blue–yellow.[15] Red–green cells compare the relative amounts of red–green in one part of a scene with the amount of red–green in an adjacent part of the scene,

Color vision 59

responding best to local color contrast (red next to green). Modeling studies have shown that double-opponent cellsare ideal candidates for the neural machinery of color constancy explained by Edwin H. Land in his retinextheory.[16]

This image (when viewed in full size, 1000 pixelswide) contains 1 million pixels, each of a

different color. The human eye can distinguishabout 10 million different colors.[17]

From the V1 blobs, color information is sent to cells in the secondvisual area, V2. The cells in V2 that are most strongly color tuned areclustered in the "thin stripes" that, like the blobs in V1, stain for theenzyme cytochrome oxidase (separating the thin stripes are interstripesand thick stripes, which seem to be concerned with other visualinformation like motion and high-resolution form). Neurons in V2 thensynapse onto cells in the extended V4. This area includes not only V4,but two other areas in the posterior inferior temporal cortex, anterior toarea V3, the dorsal posterior inferior temporal cortex, and posteriorTEO.[18] [19] (Area V4 was identified by Semir Zeki to be exclusivelydedicated to color, but this has since been shown not to be the case.[20]

Color processing in the extended V4 occurs in millimeter-sized colormodules called globs.[18] [19] This is the first part of the brain in whichcolor is processed in terms of the full range of hues found in colorspace.[18] [19]

Anatomical studies have shown that neurons in extended V4 provide input to the inferior temporal lobe . "IT" cortexis thought to integrate color information with shape and form, although it has been difficult to define the appropriatecriteria for this claim. Despite this murkiness, it has been useful to characterize this pathway (V1 > V2 > V4 > IT) asthe ventral stream or the "what pathway", distinguished from the dorsal stream ("where pathway") that is thought toanalyze motion, among many other features.

Subjectivity of color perception

Side by side comparison of the same rainbow photo in color and monochrome.The stripes of color, perceived vividly by most people, totally disappear when

the color saturation is set to zero.

It has been established[21] that the Himbapeople perceive colors differently from mostEuro-Americans - they easily distinguish closeshades of green, barely discernable for mostpeople. The leading explanation is that theHimba created a very different color schemewhich divides the spectrum to dark shades(Zuzu in Himba), very light (Vapa), Vivid blueand green (Buru) and dry colors - probably dueto their specific way of life. However otherexplanations exist that have not been ruled outyet.

An example of the subjectivity of color occursin a rainbow. In a rainbow (or a spectrum oflight projected from a prism), the changesbetween wavelengths of light are smooth andcontinuous; there are no breaks or boundariescorresponding to the "bands of color" which are seen subjectively by the eye. A black-and-white photograph of arainbow shows no band stucture at all, demonstrating that the number of bands, and the bands themselves, arephenomena added to nature by the eye and the brain. They are not objectively real any more than "hot" or "cold."

Color vision 60

The cone photoreceptors, which begin the process that results in the ultimate sensation of color in the brain, aresensitive to different portions of the visible spectrum. For humans, the visible spectrum ranges approximately from380 to 740 nm, and there are normally three types of cones. The number of colors that can be distinguished by thesecones is in principle unlimited and in practice extremely large.The sensation of color is also heavily dependent on contrast with surroundings. For example, a 'red' piece ofconstruction paper or red filing folder does not reflect pure monochromatic "red" light.[22] Rather, it absorbs a largerfraction of other frequencies of visible light shining upon it than those in a group of frequencies that are perceived asred when they are viewed alone. However, although the red paper reflects more of light near the red end of thespectrum, it reflects some of all frequencies (not only red), and a room lit with only the reflection from a red piece ofpaper would soon appear to be normally lit to an adapted eye, and would allow visualization of all of the other colorspresent in the room. A red-colored paper is therefore perceived to be red mainly by contrast with its surroundings,because the human eye can distinguish between different wavelengths, and the brain creates the separate sensation of"red" as a helper in discriminating one object from another, or from its background. Color, which in nature is neverconstructed from pure frequencies of light, is a quality constructed by the visual brain from spectral reflectance, theobjective property of objects. The advantage of color perception is the better discrimination of surfaces allowed bythis aspect of visual processing, which makes quite similar surfaces into very different perceptions.

In animalsThe visible range and number of cone types differ between species. Mammals in general have color vision of alimited type, and are usually red-green color-blind, with only two types of cones. Humans, some primates, and somemarsupials see an extended range of colors, but only by comparison with other mammals. Most non-mammalianvertebrate species distinguish different colors at least as well as humans, and many species of birds, fish, reptiles andamphibians, as well as some invertebrates, have more than three cone types and probably superior color vision tohumans.In most Catarrhini (Old World monkeys and apes — primates closely related to humans) there are three types ofcolor receptors (known as cone cells), resulting in trichromatic color vision. These primates, like humans, are knownas trichromats. Many other primates and other mammals are dichromats, which is the general color vision state formammals that are active during the day (i.e., felines, canines, ungulates). Nocturnal mammals may have little or nocolor vision. Trichromat non-primate mammals are rare.[5] [23]

Many invertebrates have color vision. Honey- and bumblebees have trichromatic color vision, which is insensitive tored but sensitive in ultraviolet. In view of the importance of colour vision to bees one might expect these receptorsensitivities to reflect their specific visual ecology; for example the types of flowers that they visit. However, themain groups of hymenopteran insects excluding ants (i.e. bees, wasps and sawflies) mostly have three types ofphotoreceptor, with spectral sensitivities similar the honeybee’s.[24] Papilio butterflies possess six types ofphotoreceptors and may have pentachromatic vision.[25] The most complex color vision system in animal kingdomhas been found in stomatopods (such as the mantis shrimp) with up to 12 different spectral receptor types thought towork as multiple dichromatic units.[26]

Vertebrate animals such as tropical fish and birds sometimes have more complex color vision systems than humans;thus the many subtle colors they exhibit generally serve as direct signals between fish or between birds, and are notintended to signal mammals.[27] In the birds, tetrachromacy is achieved through up to four cone types, depending onspecies.Each single cone contains one of the four main types of vertebrate cone photopigment (LWS/ MWS, RH2,SWS2 and SWS1and has a coloured oil droplet in its inner segment.[28] Brightly colored oil droplets inside the conesshift or narrow the spectral sensitivity of the cell. It has been suggested that it is likely that pigeons arepentachromats.Reptiles and amphibians also have four cone types (occasionally five), and probably see at least the same number of colors that humans do, or perhaps more. In addition, some nocturnal geckos have the capability of seeing color in

Color vision 61

dim light.[29]

In the evolution of mammals, segments of color vision were lost, then for a few species of primates, regained bygene duplication. Eutherian mammals other than primates (for example, dogs, cats, mammalian farm animals)generally have less-effective two-receptor (dichromatic) color perception systems, which distinguish blue, green, andyellow—but cannot distinguish oranges and reds. The adaptation to see reds is particularly important for primatemammals, since it leads to identification of fruits, and also newly sprouting reddish leaves, which are particularlynutritious.However, even among primates, full color vision differs between New World and Old World monkeys. Old Worldprimates, including monkeys and all apes, have vision similar to humans. New World monkeys may or may not havecolor sensitivity at this level: in most species, males are dichromats, and about 60% of females are trichromats, butthe owl monkeys are cone monochromats, and both sexes of howler monkeys are trichromats.[30] [31] [32] [33] Visualsensitivity differences between males and females in a single species is due to the gene for yellow-green sensitiveopsin protein (which confers ability to differentiate red from green) residing on the X sex chromosome.Several marsupials such as the fat-tailed dunnart (Sminthopsis crassicaudata) have been shown to have trichromaticcolor vision.[34]

Marine mammals, adapted for low-light vision, have only a single cone type and are thus monochromats.

EvolutionColor perception mechanisms are highly dependent on evolutionary factors, of which the most prominent is thoughtto be satisfactory recognition of food sources. In herbivorous primates, color perception is essential for findingproper (immature) leaves. In hummingbirds, particular flower types are often recognized by color as well. On theother hand, nocturnal mammals have less-developed color vision, since adequate light is needed for cones tofunction properly. There is evidence that ultraviolet light plays a part in color perception in many branches of theanimal kingdom, especially insects. In general, the optical spectrum encompasses the most common electronictransitions in matter and is therefore the most useful for collecting information about the environment.The evolution of trichromatic color vision in primates occurred as the ancestors of modern monkeys, apes, andhumans switched to diurnal (daytime) activity and began consuming fruits and leaves from flowering plants.[35]

Color vision, with UV discrimination, is also present in a number of arthropods – the only terrestrial animals besidesthe vertebrates to possess this trait.[36]

Some animals can distinguish colors in the ultraviolet spectrum. The UV spectrum falls outside the human visiblerange, except for some cataract surgery patients.[37] Birds, turtles, lizards, many fish and some rodents have UVreceptors in their retinas.[38] These animals can see the UV patterns found on flowers and other wildlife that areotherwise invisible to the human eye.UV and multi-dimensional vision is an especially important adaptation in birds. It allows birds to spot small preyfrom a distance, navigate, avoid predators, and forage while flying at high speeds. Birds also utilize their broadspectrum vision to recognize other birds, and in sexual selection.[39] [40]

Mathematics of color perceptionA "physical color" is a combination of pure spectral colors (in the visible range). Since there are, in principle,infinitely many distinct spectral colors, the set of all physical colors may be thought of as an infinite-dimensionalvector space, in fact a Hilbert space. We call this space Hcolor. More technically, the space of physical colors may beconsidered to be the (mathematical) cone over the simplex whose vertices are the spectral colors, with white at thecentroid of the simplex, black at the apex of the cone, and the monochromatic color associated with any given vertexsomewhere along the line from that vertex to the apex depending on its brightness.

Color vision 62

An element C of Hcolor is a function from the range of visible wavelengths—considered as an interval of realnumbers [Wmin,Wmax]—to the real numbers, assigning to each wavelength w in [Wmin,Wmax] its intensity C(w).A humanly perceived color may be modeled as three numbers: the extents to which each of the 3 types of cones isstimulated. Thus a humanly perceived color may be thought of as a point in 3-dimensional Euclidean space. We callthis space R3

color.Since each wavelength w stimulates each of the 3 types of cone cells to a known extent, these extents may berepresented by 3 functions s(w), m(w), l(w) corresponding to the response of the S, M, and L cone cells, respectively.Finally, since a beam of light can be composed of many different wavelengths, to determine the extent to which aphysical color C in Hcolor stimulates each cone cell, we must calculate the integral (with respect to w), over theinterval [Wmin,Wmax], of C(w)·s(w), of C(w)·m(w), and of C(w)·l(w). The triple of resulting numbers associates toeach physical color C (which is an element in Hcolor) to a particular perceived color (which is a single point inR3

color). This association is easily seen to be linear. It may also easily be seen that many different elements in the"physical" space Hcolor can all result in the same single perceived color in R3

color, so a perceived color is not uniqueto one physical color.Thus human color perception is determined by a specific, non-unique linear mapping from the infinite-dimensionalHilbert space Hcolor to the 3-dimensional Euclidean space R3

color.Technically, the image of the (mathematical) cone over the simplex whose vertices are the spectral colors, by thislinear mapping, is also a (mathematical) cone in R3

color. Moving directly away from the vertex of this conerepresents maintaining the same chromaticity while increasing its intensity. Taking a cross-section of this cone yieldsa 2D chromaticity space. Both the 3D cone and its projection or cross-section are convex sets; that is, any mixture ofspectral colors is also a color.

Color vision 63

The CIE 1931 xy chromaticity diagram. The Planckian locus is shown with colortemperatures labeled in degrees Kelvin. The outer curved boundary is the spectral(or monochromatic) locus, with wavelengths shown in nanometers (blue). Note

that the colors in this file are being specified using sRGB. Areas outside thetriangle cannot be accurately rendered because they are out of the gamut of sRGB,therefore they have been interpreted. Note that the colors depicted depend on thecolor space of the device you use to view the image (number of colors on yourmonitor, etc.), and may not be a strictly accurate representation of the color at a

particular position.

In practice, it would be quite difficult tophysiologically measure an individual'sthree cone responses to various physicalcolor stimuli. Instead, a psychophysicalapproach is taken. Three specific benchmarktest lights are typically used; let us call themS, M, and L. To calibrate human perceptualspace, scientists allowed human subjects totry to match any physical color by turningdials to create specific combinations ofintensities (IS, IM, IL) for the S, M, and Llights, resp., until a match was found. Thisneeded only to be done for physical colorsthat are spectral (since a linear combinationof spectral colors will be matched by thesame linear combination of their (IS, IM, IL)matches. Note that in practice, often at leastone of S, M, L would have to be added withsome intensity to the physical test color, andthat combination matched by a linearcombination of the remaining 2 lights.Across different individuals (without colorblindness), the matchings turned out to benearly identical.

By considering all the resultingcombinations of intensities (IS, IM, IL) as asubset of 3-space, a model for humanperceptual color space is formed. (Note thatwhen one of S, M, L had to be added to the test color, its intensity was counted as negative.) Again, this turns out tobe a (mathematical) cone, not a quadric, but rather all rays through the origin in 3-space passing through a certainconvex set. Again, this cone has the property that moving directly away from the origin corresponds to increasing theintensity of the S, M, L lights proportionately. Again, a cross-section of this cone is a planar shape that is (bydefinition) the space of "chromaticities" (informally: distinct colors); one particular such cross section,corresponding to constant X+Y+Z of the CIE 1931 color space, gives the CIE chromaticity diagram.

It should be noted that this system implies that for any hue or non-spectral color not on the boundary of thechromaticity diagram, there are infinitely many distinct physical spectra that are all perceived as that hue or color.So, in general there is no such thing as the combination of spectral colors that we perceive as (say) a specific versionof tan; instead there are infinitely many possibilities that produce that exact color. The boundary colors that are purespectral colors can be perceived only in response to light that is purely at the associated wavelength, while theboundary colors on the "line of purples" can each only be generated by a specific ratio of the pure violet and the purered at the ends of the visible spectral colors.The CIE chromaticity diagram is horseshoe-shaped, with its curved edge corresponding to all spectral colors (thespectral locus), and the remaining straight edge corresponding to the most saturated purples, mixtures of red andviolet.

Color vision 64

Chromatic adaptationIn color science, chromatic adaptation is the estimation of the representation of an object under a different lightsource than the one in which it was recorded. A common application is to find a chromatic adaptation transform(CAT) that will make the recording of a neutral object appear neutral (color balance), while keeping other colors alsolooking realistic.[41] For example, chromatic adaptation transforms are used when converting images between ICCprofiles with different white points. Adobe Photoshop, for example, uses the Bradford CAT.[42]

In color vision, chromatic adaptation refers to color constancy; the ability of the visual system to preserve theappearance of an object under a wide range of light sources.[43]

References[1] "Eye, human." Encyclopædia Britannica 2006 Ultimate Reference Suite DVD, 2009.[2] Neitz J, Jacobs GH (1986). "Polymorphism of the long-wavelength cone in normal human color vision" (http:/ / www. nature. com/ nature/

journal/ v323/ n6089/ abs/ 323623a0. html). Nature 323 (6089): 623–5. doi:10.1038/323623a0. PMID 3773989. .[3] Jacobs GH (January 1996). "Primate photopigments and primate color vision". Proc. Natl. Acad. Sci. U.S.A. 93 (2): 577–81.

doi:10.1073/pnas.93.2.577. PMC 40094. PMID 8570598.[4] Hering, Ewald (1872). "Zur Lehre vom Lichtsinne" (http:/ / books. google. com/ ?id=u5MCAAAAYAAJ& pg=PA5& lpg=PA5& dq=1872+

hering+ ewald+ Zur+ Lehre+ vom+ Lichtsinne. + Sitzungsberichte+ der+ kaiserlichen+ Akademie+ der+ Wissenschaften. +Mathematischâ��naturwissenschaftliche+ Classe,). Sitzungsberichte der Mathematisch–Naturwissenschaftliche Classe der KaiserlichenAkademie der Wissenschaften (K.-K. Hof- und Staatsdruckerei in Commission bei C. Gerold's Sohn) LXVI. Band (III Abtheilung). .

[5] Ali, M.A. & Klyne, M.A. (1985), p.168[6] Wyszecki, Günther; Stiles, W.S. (1982). Color Science: Concepts and Methods, Quantitative Data and Formulae (2nd ed.). New York:

Wiley Series in Pure and Applied Optics. ISBN 0-471-02106-7.[7] R. W. G. Hunt (2004). The Reproduction of Colour (6th ed.). Chichester UK: Wiley–IS&T Series in Imaging Science and Technology.

pp. 11–2. ISBN 0-470-02425-9.[8] Verrelli BC, Tishkoff SA (September 2004). "Signatures of Selection and Gene Conversion Associated with Human Color Vision Variation".

Am. J. Hum. Genet. 75 (3): 363–75. doi:10.1086/423287. PMC 1182016. PMID 15252758.[9] Roth, Mark (2006). "Some women may see 100 million colors, thanks to their genes" (http:/ / www. post-gazette. com/ pg/ 06256/

721190-114. stm) Post-Gazette.com[10] R.W. Rodieck, "The First Steps in Seeing". Sinauer Associates, Inc., Sunderland, Massachusetts, USA, 1998.[11] SH Hendry, RC Reid, "The Koniocellular Pathway in Primate Vision". Annual Reviews Neuroscience, 2000, vol. 23, pp. 127-53 (http:/ /

www. annualreviews. org/ doi/ abs/ 10. 1146/ annurev. neuro. 23. 1. 127?url_ver=Z39. 88-2003& rfr_id=ori:rid:crossref. org&rfr_dat=cr_pub=ncbi. nlm. nih. gov)

[12] Nigel W. Daw (17 November 1967). "Goldfish Retina: Organization for Simultaneous Color Contrast". Science 158 (3803): 942–4.doi:10.1126/science.158.3803.942. PMID 6054169.

[13] Bevil R. Conway (2002). Neural Mechanisms of Color Vision: Double-Opponent Cells in the Visual Cortex (http:/ / books. google. com/?id=pFodUlHfQmcC& pg=PR7& dq=goldfish+ retina+ by+ Nigel-Daw). Springer. ISBN 1402070926. .

[14] Conway BR (15 April 2001). "Spatial structure of cone inputs to color cells in alert macaque primary visual cortex (V-1)" (http:/ / www.jneurosci. org/ content/ 21/ 8/ 2768. full). J. Neurosci. 21 (8): 2768–83. PMID 11306629. .

[15] John E. Dowling (2001). Neurons and Networks: An Introduction to Behavioral Neuroscience (http:/ / books. google. com/?id=adeUwgfwdKwC& pg=PA376& dq=Margaret+ Livingstone+ David+ Hubel+ double+ opponent+ blobs). Harvard University Press.ISBN 0674004620. .

[16] McCann, M., ed. 1993. Edwin H. Land's Essays. Springfield, Va.: Society for Imaging Science and Technology.[17] Judd, Deane B.; Wyszecki, Günter (1975). Color in Business, Science and Industry. Wiley Series in Pure and Applied Optics (3rd ed.). New

York: Wiley-Interscience. p. 388. ISBN 0471452122.[18] Conway BR, Moeller S, Tsao DY (2007). "Specialized color modules in macaque extrastriate cortex". Neuron 56 (3): 560–73.

doi:10.1016/j.neuron.2007.10.008. PMID 17988638.[19] Conway BR, Tsao DY (2009). "Color-tuned neurons are spatially clustered according to color preference within alert macaque posterior

inferior temporal cortex". Proc Natl Acad Sci U S A 106 (42): 18035–18039. doi:10.1073/pnas.0810943106. PMC 2764907. PMID 19805195.[20] John Allman and Steven W. Zucker (1993). "On cytochrome oxidase blobs in visual cortex" (http:/ / books. google. com/

?id=eWBiKaOCNIYC& pg=PA34& dq=v4+ zeki+ color). In Laurence Harris and Michael Jenkin, editors. Spatial Vision in Humans andRobots: The Proceedings of the 1991 York Conference. Cambridge University Press. ISBN 0521430712. .

[21] Roberson, Davidoff, Davies & Shapiro. referred by Debi Roberson, University of Essex 2011[22] Wright, W. D. (1967). The rays are not coloured: essays on the science and vision and colour. Bristol: Hilger. ISBN 0-85274-068-9.[23] For .pdf online review see: (http:/ / onlinelibrary. wiley. com/ doi/ 10. 1111/ j. 1469-185X. 1993. tb00738. x/ abstract) THE

DISTRIBUTION AND NATURE OF COLOUR VISION AMONG THE MAMMALS. GERALD H. JACOBS Biological Reviews Volume

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68, Issue 3, pages 413–471, August 1993. DOI: 10.1111/j.1469-185X.1993.tb00738.x[24] Osorio D, Vorobyev M (June 2008). A review of the evolution of animal colour vision and visual communication signals journal=Vision

Research. 48. pp. 2042–2051. doi:10.1016/j.visres.[25] Arikawa K (November 2003). "Spectral organization of the eye of a butterfly, Papilio" (http:/ / www. springerlink. com/ content/

whjepqnhpulyeevk/ ). J. Comp. Physiol. A Neuroethol. Sens. Neural. Behav. Physiol. 189 (11): 791–800. doi:10.1007/s00359-003-0454-7.PMID 14520495. .

[26] Cronin TW, Marshall NJ (1989). "A retina with at least ten spectral types of photoreceptors in a mantis shrimp" (http:/ / www. nature. com/nature/ journal/ v339/ n6220/ abs/ 339137a0. html). Nature 339 (6220): 137–40. doi:10.1038/339137a0. .

[27] Kelber A, Vorobyev M, Osorio D (February 2003). "Animal color vision—behavioural tests and physiological concepts". Biol Rev CambPhilos Soc 78 (1): 81–118. doi:10.1017/S1464793102005985. PMID 12620062.

[28] Osorio D, Vorobyev M (June 2008). A review of the evolution of animal colour vision and visual communication signals journal=VisionResearch. 48. pp. 2042–2051. doi:10.1016/j.visres.

[29] Roth, Lina S. V.; Lundström, Linda; Kelber, Almut; Kröger, Ronald H. H.; Unsbo, Peter (March 30, 2009). "The pupils and optical systemsof gecko eyes" (http:/ / www. journalofvision. org/ content/ 9/ 3/ 27). Journal of Vision 9 (3:27): 1–11. doi:10.1167/9.3.27. PMID 19757966. .

[30] Jacobs G. H., Deegan J. F. (2001). "Photopigments and color vision in New World monkeys from the family Atelidae". Proceedings of theRoyal Society of London, Series B 268 (1468): 695–702. doi:10.1098/rspb.2000.1421.

[31] Jacobs G. H., Deegan J. F., Neitz , Neitz J., Crognale M. A. (1993). "Photopigments and color vision in the nocturnal monkey, Aotus".Vision Research 33 (13): 1773–1783. doi:10.1016/0042-6989(93)90168-V. PMID 8266633.

[32] Mollon J. D., Bowmaker J. K., Jacobs G. H. (1984). "Variations of color vision in a New World primate can be explained by polymorphismof retinal photopigments". Proceedings of the Royal Society of London, Series B 222 (1228): 373–399. doi:10.1098/rspb.1984.0071.

[33] Sternberg, Robert J. (2006): Cognitive Psychology. 4th Ed. Thomson Wadsworth.[34] Arrese CA, Beazley LD, Neumeyer C (March 2006). "Behavioural evidence for marsupial trichromacy". Curr. Biol. 16 (6): R193–4.

doi:10.1016/j.cub.2006.02.036. PMID 16546067.[35] Pinker, Steven (1997). How the Mind Works. New York: Norton. p. 191. ISBN 0-393-04535-8.[36] Koyanagi, M.; Nagata, T.; Katoh, K.; Yamashita, S.; Tokunaga, F. (2008). "Molecular Evolution of Arthropod Color Vision Deduced from

Multiple Opsin Genes of Jumping Spiders". Journal of Molecular Evolution 66 (2): 130. doi:10.1007/s00239-008-9065-9. PMID 18217181.[37] David Hambling (May 30, 2002). "Let the light shine in: You don't have to come from another planet to see ultraviolet light" (http:/ / www.

guardian. co. uk/ science/ 2002/ may/ 30/ medicalscience. research). EducationGuardian.co.uk. .[38] Jacobs GH, Neitz J, Deegan JF (1991). "Retinal receptors in rodents maximally sensitive to ultraviolet light" (http:/ / www. nature. com/

nature/ journal/ v353/ n6345/ abs/ 353655a0. html). Nature 353 (6345): 655–6. doi:10.1038/353655a0. PMID 1922382. .[39] FJ Varela, AG Palacios, and TM Goldsmith (1993). Bischof, Hans-Joachim; Zeigler, H. Philip. ed. Vision, brain, and behavior in birds.

Cambridge, Mass: MIT Press. pp. 77–94. ISBN 0-262-24036-X.[40] IC Cuthill, JC Partridge, ATD Bennett, SC Church, NS Hart, and S Hunt (2000). "Ultraviolet Vision in Birds". Advances in the Study of

Behavior. 29. pp. 159–214.[41] Süsstrunk, Sabine. Chromatic Adaptation (http:/ / ivrgwww. epfl. ch/ research/ past_topics/ chromatic_adaptation. html)[42] Lindbloom, Bruce. Chromatic Adaptation (http:/ / www. brucelindbloom. com/ Eqn_ChromAdapt. html)[43] Fairchild, Mark D. (2005). "8. Chromatic Adaptation" (http:/ / books. google. com/ ?id=8_TxzK2B-5MC& pg=PA146& dq="chromatic+

adaptation"). Color Appearance Models. Wiley. p. 146. ISBN 0470012161. .

External links• Peter Gouras, "Color Vision" (http:/ / webvision. med. utah. edu/ book/ part-vii-color-vision/ color-vision/ ),

Webvision, University of Utah School of Medicine, May 2009.• Kenneth R. Koehler, "Spectral Sensitivity of the Eye" (http:/ / www. rwc. uc. edu/ koehler/ biophys/ 6d. html),

College Physics for Students of Biology and Chemistry, University of Cincinnati Raymond Walters College,1996.

• James T. Fulton, "The Human is a Blocked Tetrachromat" (http:/ / www. neuronresearch. net/ vision/ files/tetrachromat. htm), Neural Concepts, July 2009.

• Vurdlak, "Mega Color Blindness Test" (http:/ / www. moillusions. com/ 2009/ 03/ mega-color-blindness-test.html), Mighty Optical Illusions, March 2009.

• Clive Maxfield and Alvin Brown, "Color Vision: One of Nature's Wonders" (http:/ / www. diycalculator. com/sp-cvision. shtml), DIYCalculator.com, 2006.

• Chenguang Lu, "The decoding model: a symmetrical model of color vision" (http:/ / survivor99. com/ colorforum/The Decoding Model. html).

• Egopont, "Color Vision Test" (http:/ / www. egopont. com/ colorvision. php).

Visual perception 66

Visual perceptionVisual perception is the ability to interpret information and surroundings from the effects of visible light reachingthe eye. The resulting perception is also known as eyesight, sight, or vision (adjectival form: visual, optical, orocular). The various physiological components involved in vision are referred to collectively as the visual system,and are the focus of much research in psychology, cognitive science, neuroscience, and molecular biology.

Visual systemThe visual system in humans and animals allows individuals to assimilate information from the environment. The actof seeing starts when the lens of the eye focuses an image of its surroundings onto a light-sensitive membrane in theback of the eye, called the retina. The retina is actually part of the brain that is isolated to serve as a transducer forthe conversion of patterns of light into neuronal signals. The lens of the eye focuses light on the photoreceptive cellsof the retina, which detect the photons of light and respond by producing neural impulses. These signals areprocessed in a hierarchical fashion by different parts of the brain, from the retina upstream to central ganglia in thebrain.Note that up until now the above paragraph could apply to octopi, molluscs, worms, insects and things moreprimitive; anything with a more concentrated nervous system and better eyes than say a jellyfish. However, thefollowing applies to mammals generally and birds (in modified form): The retina in these more complex animalssends fibers (the optic nerve) to the lateral geniculate nucleus, to the primary and secondary visual cortex of thebrain. Signals from the retina can also travel directly from the retina to the superior colliculus.

Study of visual perceptionThe major problem in visual perception is that what people see is not simply a translation of retinal stimuli (i.e., theimage on the retina). Thus people interested in perception have long struggled to explain what visual processing doesto create what is actually seen.

Early studies

The visual dorsal stream (green) and ventral stream (purple) are shown. Much ofthe human cerebral cortex is involved in vision.

There were two major ancient Greekschools, providing a primitive explanationof how vision is carried out in the body.

The first was the "emission theory" whichmaintained that vision occurs when raysemanate from the eyes and are interceptedby visual objects. If an object was seendirectly it was by 'means of rays' coming outof the eyes and again falling on the object. Arefracted image was, however, seen by'means of rays' as well, which came out ofthe eyes, traversed through the air, and afterrefraction, fell on the visible object whichwas sighted as the result of the movement ofthe rays from the eye. This theory waschampioned by scholars like Euclid andPtolemy and their followers.

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The second school advocated the so called 'intro-mission' approach which sees vision as coming from somethingentering the eyes representative of the object. With its main propagators Aristotle, Galen and their followers, thistheory seems to have some contact with modern theories of what vision really is, but it remained only a speculationlacking any experimental foundation.Both schools of thought relied upon the principle that "like is only known by like", and thus upon the notion that theeye was composed of some "internal fire" which interacted with the "external fire" of visible light and made visionpossible. Plato makes this assertion in his dialogue Timaeus, as does Aristotle, in his De Sensu.[1]

Leonardo DaVinci: The eye has a central line andeverything that reaches the eye through this

central line can be seen distinctly.

Alhazen (965 – c. 1040) carried out many investigations andexperiments on visual perception, extended the work of Ptolemy onbinocular vision, and commented on the anatomical works of Galen.[2]

[3]

Leonardo DaVinci (1452–1519) was the first to recognize the specialoptical qualities of the eye. He wrote "The function of the human eye... was described by a large number of authors in a certain way. But Ifound it to be completely different." His main experimental findingwas that there is only a distinct and clear vision at the line of sight, theoptical line that ends at the fovea. Although he did not use these wordsliterally he actually is the father of the modern distinction betweenfoveal and peripheral vision.

Unconscious inferenceHermann von Helmholtz is often credited with the first study of visual perception in modern times. Helmholtzexamined the human eye and concluded that it was, optically, rather poor. The poor-quality information gathered viathe eye seemed to him to make vision impossible. He therefore concluded that vision could only be the result ofsome form of unconscious inferences: a matter of making assumptions and conclusions from incomplete data, basedon previous experiences.Inference requires prior experience of the world.Examples of well-known assumptions, based on visual experience, are:• light comes from above• objects are normally not viewed from below• faces are seen (and recognized) upright.[4]

The study of visual illusions (cases when the inference process goes wrong) has yielded much insight into what sortof assumptions the visual system makes.Another type of the unconscious inference hypothesis (based on probabilities) has recently been revived in so-calledBayesian studies of visual perception. Proponents of this approach consider that the visual system performs someform of Bayesian inference to derive a perception from sensory data. Models based on this idea have been used todescribe various visual subsystems, such as the perception of motion or the perception of depth.[5] [6] The "whollyempirical theory of perception" is a related and newer approach that rationalizes visual perception without explicitlyinvoking Bayesian formalisms.[7]

[8] ===Gestalt theory=== Gestalt psychologists working primarily in the 1930s and 1940s raised many of theresearch questions that are studied by vision scientists today.The Gestalt Laws of Organization have guided the study of how people perceive visual components as organized patterns or wholes, instead of many different parts. Gestalt is a German word that partially translates to "configuration or pattern" along with "whole or emergent structure." According to this theory, there are six main factors that determine how the visual system automatically groups elements into patterns which are as follows:

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1)Law of Proximity: A notion which induces the grouping of objects that are close to each other. 2)Law ofSimilarity: A phenomenon which enables things to coagulate into a specific form based on how similar they are. 3)Law of Closure: This Gestalt theory suggests that when an object is occluded, the visual system of the humanspecies tends to "fill in" the missing spaces. 4) Law of Common Fate(i.e. common motion): This law states thatwhen objects move together, they give rise to the perception of a common element. 5) Law of Continuity: ThisGestalt law of organization establishes that the visual system tends to perceive hidden parts of a pattern as continuingin a predictable and basic manner.

Analysis of eye movement

Eye movement first 2 seconds (Yarbus, 1967)

During the 1960s, technical development permitted the continuousregistration of eye movement during reading[9] in picture viewing[10]

and later in visual problem solving[11] and when headset-camerasbecame available, also during driving.[12]

The picture to the left shows what may happen during the first twoseconds of visual inspection. While the background is out of focus,representing the peripheral vision, the first eye movement goes to theboots of the man (just because they are very near the starting fixationand have a reasonable contrast).

The following fixations jump from face to face. They might even permit comparisons between faces.It may be concluded that the icon face is a very attractive search icon within the peripheral field of vision. The fovealvision adds detailed information to the peripheral first impression.It can also be noted that there are three different types of eye movements: vergence movements, saccadic movementsand pursuit movements. Vergence movements involve the cooperation of both eyes to allow for an image to fall onthe same area of both retinas. This results in a single focused image. Saccadic movements is the type of eyemovement that is used to rapidly scan a particular scene/image. Lastly, pursuit movement is used to follow objectsin motion. [13]

The cognitive and computational approachesThe major problem with the Gestalt laws (and the Gestalt school generally) is that they are descriptive notexplanatory. For example, one cannot explain how humans see continuous contours by simply stating that the brain"prefers good continuity". Computational models of vision have had more success in explaining visual phenomenaand have largely superseded Gestalt theory. More recently, the computational models of visual perception have beendeveloped for Virtual Reality systems — these are closer to real life situation as they account for motion andactivities which populate the real world.[14] Regarding Gestalt influence on the study of visual perception, Bruce,Green & Georgeson conclude:

"The physiological theory of the Gestaltists has fallen by the wayside, leaving us with a set of descriptiveprinciples, but without a model of perceptual processing. Indeed, some of their "laws" of perceptualorganisation today sound vague and inadequate. What is meant by a "good" or "simple" shape, for example?"[15]

In the 1970s David Marr developed a multi-level theory of vision, which analysed the process of vision at differentlevels of abstraction. In order to focus on the understanding of specific problems in vision, he identified three levelsof analysis: the computational, algorithmic and implementational levels. Many vision scientists, including TomasoPoggio, have embraced these levels of analysis and employed them to further characterize vision from acomputational perspective.

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The computational level addresses, at a high level of abstraction, the problems that the visual system must overcome.The algorithmic level attempts to identify the strategy that may be used to solve these problems. Finally, theimplementational level attempts to explain how these problems are overcome in terms of the actual neural activitynecessary.Marr suggested that it is possible to investigate vision at any of these levels independently. Marr described vision asproceeding from a two-dimensional visual array (on the retina) to a three-dimensional description of the world asoutput. His stages of vision include:• a 2D or primal sketch of the scene, based on feature extraction of fundamental components of the scene, including

edges, regions, etc. Note the similarity in concept to a pencil sketch drawn quickly by an artist as an impression.• a 2½ D sketch of the scene, where textures are acknowledged, etc. Note the similarity in concept to the stage in

drawing where an artist highlights or shades areas of a scene, to provide depth.• a 3 D model, where the scene is visualized in a continuous, 3-dimensional map.[16]

TransductionTransduction is the process through which energy from environmental stimuli is converted to neural activity for thebrain to understand and process. The back of the eye contains three different cell layers; Photoreceptor layer, Bipolarcell layer and Ganglion cell layer. The photoreceptor layer is at the very back and contains rod photoreceptors andcone photoreceptors. Cones are responsible for colour perception. There are three different cones: red, green andblue. Photoreceptors contain within them photopigments, composed of two molecules. There are 4 specificphotopigments (each with their own colour) that respond to specific wavelengths of light. When the appropriatewavelength of light hits the photoreceptor, its photopigment splits into two, which sends a message to the bipolar celllayer, which in turn sends a message to the ganglion cells, which then send the information through the optic nerveto the brain. If the appropriate photopigment is not in the proper photoreceptor (for example, a green photopigmentinside a red cone), a condition called colour blindness will occur. There are three types of colour blindness:Protanopia, deuteranopia and tritanopia.[17]

Opponent ProcessTransduction involves chemical messages sent from the photoreceptors to the bipolar cells to the ganglion cells.Several photoreceptors may send their information to one ganglion cell. There are two types of ganglion cells: red /green and yellow/blue. These neuron cells consistently fire – even when not stimulated. The brain interprets differentcolours (and with a lot of information, an image) when the rate of firing of these neurons alters. Red light stimulatesthe red cone, which in turn stimulates the red/green ganglion cell. Likewise, green light stimulates the green cone,which stimulates the red/green ganglion cell and blue light stimulates the blue cone which stimulates the yellow/blueganglion cell. The rate of firing of the ganglion cells is increased when it is signalled by one cone and decreased(inhibited) when it is signalled by the other cone. The first colour in the name if the ganglion cell is the colour thatexcites it and the second is the colour that inhibits it. I.e.: A red cone would excite the red/green ganglion cell and thegreen cone would inhibit the red/green ganglion cell. This is an opponent process. If the rate of firing of a red/greenganglion cell is increased, the brain would know that the light was red, if the rate was decreased, the brain wouldknow that the colour of the light was green.[18]

Visual perception 70

Artificial visual perceptionThe theory and the observations on visual perception have been the main source of inspiration for computer vision(also called machine vision, or computational vision). Special hardware structures and software algorithms providemachines with the capability to interpret the images coming from a camera or a sensor. Artificial Visual Perceptionhas long been used in the industry and is now entering the domains of automotive and robotics.

References[1] Finger, Stanley. Origins of Neuroscience. A History of Explorations into Brain Function. New York: Oxford University Press, USA, 1994.[2] Howard, I (1996). "Alhazen's neglected discoveries of visual phenomena". Perception 25 (10): 1203–1217. doi:10.1068/p251203.

PMID 9027923.[3] Omar Khaleefa (1999). "Who Is the Founder of Psychophysics and Experimental Psychology?". American Journal of Islamic Social Sciences

16 (2).[4] Hans-Werner Hunziker, (2006) Im Auge des Lesers: foveale und periphere Wahrnehmung - vom Buchstabieren zur Lesefreude [In the eye of

the reader: foveal and peripheral perception - from letter recognition to the joy of reading] Transmedia Stäubli Verlag Zürich 2006 ISBN978-3-7266-0068-6

[5] Mamassian, Landy & Maloney (2002)[6] A Primer on Probabilistic Approaches to Visual Perception (http:/ / www. purveslab. net/ research/ primer. html)[7] The Wholly Empirical Theory of Perception (http:/ / www. purveslab. net/ research. html)[8] Carlson R., Neil (2007). Psychology the science of behaviour. Upper Saddle River,New Jersey, USA: Pearson Education Inc.. pp. 176.

ISBN 9780205645244.[9] Taylor, St.: Eye Movements in Reading: Facts and Fallacies. American Educational Research Association, 2 (4), 1965, 187-202.[10] Yarbus, A. L. (1967). Eye movements and vision, Plenum Press, New York[11] Hunziker, H. W. (1970). Visuelle Informationsaufnahme und Intelligenz: Eine Untersuchung über die I CAN'T SEE!Augenfixationen beim

Problemlösen. Schweizerische Zeitschrift für Psychologie und ihre Anwendungen, 1970, 29, Nr 1/2[12] Cohen, A. S. (1983). Informationsaufnahme beim Befahren von Kurven, Psychologie für die Praxis 2/83, Bulletin der Schweizerischen

Stiftung für Angewandte Psychologie[13] Carlson, Neil R. (2010). Psychology the Science of Behaviour. Toronto Ontario: Pearson Canada Inc.. pp. 140-141.[14] A.K.Beeharee - http:/ / www. cs. ucl. ac. uk/ staff/ A. Beeharee/ research. htm[15] Bruce, V., Green, P. & Georgeson, M. (1996). Visual perception: Physiology, psychology and ecology (3rd ed.). LEA. pp. 110.[16] Marr, D (1982). Vision: A Computational Investigation into the Human Representation and Processing of Visual Information. MIT Press.[17] Carlson, Neil R.; Heth, C. Donald (2010). "5". Psychology the science of behaviour (2nd ed.). Upper Saddle River, New Jersey, USA:

Pearson Education Inc.. pp. 138-145. ISBN 978-0-205-64524-4.[18] Carlson, Neil R.; Heth, C. Donald (2010). "5". Psychology the science of behaviour (2nd ed.). Upper Saddle River, New Jersey, USA:

Pearson Education Inc.. pp. 138-145. ISBN 978-0-205-64524-4.

External links• Visual Perception 3 - Cultural and Environmental Factors (http:/ / www. aber. ac. uk/ media/ Modules/ MC10220/

visper03. html)• Gestalt Laws (http:/ / www. sapdesignguild. org/ resources/ optical_illusions/ gestalt_laws. html)• Summary of Kosslyn et al.'s theory of high-level vision (http:/ / develintel. blogspot. com/ 2006/ 01/

kosslyns-cognitive-architecture. html)• The Organization of the Retina and Visual System (http:/ / webvision. med. utah. edu/ )• Reference info on aritificial visual perception (http:/ / www. diaplous. com/ id4. html)• Dr Trippy's Sensorium (http:/ / dr. trippy. googlepages. com) A website dedicated to the study of the human

sensorium and organisational behaviour• Effect of Detail on Visual Perception (http:/ / demonstrations. wolfram. com/ EffectOfDetailOnVisualPerception/

) by Jon McLoone, the Wolfram Demonstrations Project.• The Joy of Visual Perception (http:/ / www. yorku. ca/ eye/ toc. htm) An excellent resource on the eye's

perception abilities.• VisionScience. An Internet Resource for Research in Human and Animal Vision (http:/ / www. visionscience.

com) A most comprehensive collection of resources in vision science and perception.

Visual perception 71

• Vision and Psychophysics. (http:/ / www. cis. rit. edu/ people/ faculty/ montag/ vandplite/ course. html) A qualityaccount of many aspects of vision. However, some parts are missing.

72

Visual Color

List of colors

Color is an important part of the visual arts,fashion, interior design and many other fields and

disciplines.

The following is a comprehensive list of colors that are included in theWikipedia articles about color. A large portion of the color swatchesbelow are taken from domain-specific naming schemes such as X11 orHTML4. RGB values are given for each swatch because suchstandards are defined in terms of the sRGB color space. It is notpossible to accurately convert many of these swatches to CMYKvalues because of the differing gamuts of the two spaces, but the colormanagement systems built into operating systems and image editingsoftware attempt such conversions as accurately as possible.

The HSV (hue, saturation, value) color space values, also known asHSB (hue, saturation, brightness), and the hex triplets (for HTML webcolors) are also given in the following table. Colors that appear on the web-safe color palette — which includes thesixteen named colors — are noted.[1] (Those four named colors corresponding to the neutral grays can be renderedwith any hue value, which is effectively ignored — i.e., left blank.)

The appearance of the actual color swatches displayed below will look different on your computer depending onmany parameters, such as the properties of your display device, your color management settings and the viewingsurround conditions, most notably the color spectrum of the illumination source.[2] Also, Color naming is ambiguousand arbitrary, and varies among people and cultures, with no single swatch adequately representing any particularcolor name. Computer displays have a somewhat limited gamut, so many colorful pigments cannot be represented ona screen at all and computer simulation of the natural world is, at best, a rough approximation.

Contents:A B C D E F G H I J K L M N O P Q R S T U V W X Y ZWhite - Pink - Red - Orange - Brown - Yellow - Gray - Green - Cyan - Blue -

VioletWeb colors - Fictional colors - See also - Footnotes - References

A

Color names

Name Hex triplet Red Green Blue Hue Satur Light Satur Value W3C name

Air Force blue #5D8AA8 36% 54% 66% 204° 30% 51% 45% 66%

Alice blue #F0F8FF 94% 97% 100% 208° 100% 97% 6% 100%

Alizarin crimson #E32636 89% 15% 21% 355° 77% 52% 83% 89%

Almond #EFDECD 94% 87% 80% 30° 52% 87% 14% 94%

Amaranth #E52B50 90% 17% 31% 348° 78% 53% 81% 90%

Amber #FFBF00 100% 75% 0% 45° 100% 50% 100% 100%

Amber (SAE/ECE) #FF7E00 100% 49% 0% 30° 100% 50% 100% 100%

List of colors 73

American rose #FF033E 100% 1% 24% 345° 100% 51% 99% 87%

Amethyst #9966CC 60% 40% 80% 270° 50% 60% 50% 80%

Android Green #A4C639 64% 78% 22% 74° 55% 50% 71% 78%

Anti-flash white #F2F3F4 95% 95% 96% 210° 8% 95% 1% 96%

Antique brass #CD9575 80% 58% 46% 22° 47% 63% 43% 80%

Antique fuchsia #915C83 57% 36% 51% 316° 22% 47% 37% 57%

Antique white #FAEBD7 98% 92% 84% 34° 78% 91% 14% 98%

Ao (English) #008000 0% 50% 0% 120° 100% 25% 100% 50%

Apple green #8DB600 55% 71% 0% 74° 100% 36% 100% 71%

Apricot #FBCEB1 98% 81% 69% 24° 90% 84% 29% 98%

Aqua #00FFFF 50% 100% 83% 180° 100% 75% 100% 100%

Aquamarine #7FFFD4 18% 55% 34% 160° 50% 36% 50% 100%

Army green #4B5320 29% 33% 13% 69° 44% 23% 61% 33%

Arylide yellow #E9D66B 91% 84% 42% 51° 74% 67% 54% 91%

Ash grey #B2BEB5 70% 75% 71% 135° 9% 72% 6% 75%

Asparagus #87A96B 53% 66% 42% 93° 27% 54% 37% 66%

Atomic tangerine #FF9966 100% 60% 40% 20° 100% 70% 60% 100%

Auburn #A52A2A 65% 16% 16% 0° 59% 41% 74% 64%

Aureolin #FDEE00 99% 93% 0% 56° 100% 50% 100% 99%

AuroMetalSaurus #6E7F80 43% 50% 50% 183° 8% 47% 14% 50%

Awesome #FF2052 100% 13% 32% 347° 100% 56% 87% 100%

Azure #007FFF 0% 50% 100% 210° 100% 50% 100% 100%

Azure mist/web #F0FFFF 94% 100% 100% 180° 100% 97% 6% 100%

B

Color names

Name Hex triplet Red Green Blue Hue Satur Light Satur Value W3C name

Baby blue #89CFF0 47% 81% 94% 199° 80% 71% 43% 94%

Baby blue eyes #A1CAF1 63% 79% 95% 209° 74% 79% 33% 95%

Baby pink #F4C2C2 96% 76% 76% 30° 69% 86% 21% 96%

Ball Blue #21ABCD 13% 67% 80% 192° 72% 47% 84% 80%

Banana Mania #FAE7B5 98% 91% 71% 43° 87% 85% 28% 98%

Banana yellow #FFE135 100% 88% 21% 51° 100% 60% 79% 100%

Battleship grey #848482 52% 52% 51% 60° 1% 51% 2% 52%

Bazaar #98777B 60% 47% 48% 353° 14% 53% 22% 60%

Beau blue #BCD4E6 74% 83% 90% 206° 46% 82% 18% 90%

Beaver #9F8170 62% 51% 44% 22° 20% 53% 35% 63%

Beige #F5F5DC 96% 96% 86% 60° 56% 91% 10% 96%

List of colors 74

Bisque #FFE4C4 100% 89% 77% 33° 100% 88% 23% 100%

Bistre #3D2B1F 24% 17% 12% 24° 33% 18% 49% 24%

Bittersweet #FE6F5E 100% 44% 37% 6° 99% 68% 63% 100%

Black #000000 0% 0% 0% — 0% 0% 0% 0% Black

Blanched Almond #FFEBCD 100% 92% 80% 36° 100% 90% 20% 100%

Bleu de France #318CE7 19% 55% 91% 210° 79% 55% 79% 91%

Blizzard Blue #ACE5EE 67% 90% 93% 188° 66% 80% 28% 93%

Blond #FAF0BE 98% 94% 75% 50° 86% 86% 24% 98%

Blue #0000FF 0% 0% 100% 240° 100% 50% 100% 100% Blue

Blue (Crayola) #1F75FE 12% 46% 100% 213° 99% 56% 99% 100%

Blue (Munsell) #0093AF 0% 50% 69% 190° 100% 34% 100% 68%

Blue (NCS) #0087BD 0% 53% 74% 197° 100% 37% 100% 74%

Blue (pigment) #333399 20% 20% 60% 240° 50% 40% 67% 60%

Blue (RYB) #0247FE 1% 28% 100% 224° 99% 50% 99% 99%

Blue Bell #A2A2D0 64% 64% 82% 240° 33% 73% 22% 81%

Blue Gray #6699CC 40% 60% 80% 210° 50% 60% 50% 80%

Blue-green #0D98BA 5% 60% 73% 192° 87% 39% 93% 73%

Blue-purple #8A2BE2 54% 17% 89% 271° 76% 53% 81% 89%

Blue-violet #8A2BE2 44% 0% 100% 266° 100% 50% 81% 89%

Blush #DE5D83 87% 36% 51% 342° 66% 62% 58% 87%

Bole #79443B 47% 27% 23% 30° 34% 35% 24% 34%

Bondi blue #0095B6 0% 58% 71% 191° 100% 36% 100% 71%

Bone #E3DAC9 95% 90% 67% 48° 75% 81% 30% 95%

Boston University Red #CC0000 80% 0% 0% 0° 100% 40% 100% 80%

Bottle green #006A4E 0% 42% 31% 164° 100% 21% 100% 41%

Boysenberry #873260 53% 20% 38% 328° 46% 36% 63% 53%

Brandeis blue #0070FF 0% 44% 100% 214° 100% 50% 100% 100%

Brass #B5A642 71% 65% 26% 52° 47% 48% 64% 71%

Brick red #CB4154 80% 25% 33% 352° 57% 53% 68% 80%

Bright cerulean #1DACD6 11% 67% 84% 194° 76% 48% 86% 84%

Bright green #66FF00 40% 100% 0% 96° 100% 50% 100% 100%

Bright lavender #BF94E4 75% 58% 89% 272° 60% 74% 35% 89%

Bright maroon #C32148 76% 13% 28% 345° 71% 45% 75% 38%

Bright pink #FF007F 100% 0% 50% 330° 100% 50% 100% 100%

Bright turquoise #08E8DE 3% 91% 87% 177° 93% 47% 97% 91%

Bright ube #D19FE8 82% 62% 91% 281° 61% 77% 31% 91%

Brilliant lavender #F4BBFF 96% 73% 100% 290° 100% 87% 27% 100%

Brilliant rose #FF55A3 100% 33% 64% 332° 100% 67% 67% 100%

Brink pink #FB607F 98% 38% 50% 348° 95% 68% 62% 98%

List of colors 75

British racing green #004225 0% 26% 15% 154° 100% 13% 100% 26%

Bronze #CD7F32 80% 50% 20% 30° 61% 50% 76% 80%

Brown (traditional) #964B00 59% 29% 0% 30° 100% 29% 100% 59%

Brown (web) #A52A2A 65% 16% 16% 0° 59% 41% 75% 65%

Bubble gum #FFC1CC 99% 76% 80% 349° 91% 87% 23% 99%

Bubbles #E7FEFF 91% 100% 100% 183° 100% 95% 9% 100%

Buff #F0DC82 94% 86% 51% 49° 79% 73% 46% 94%

Bulgarian rose #480607 28% 2% 3% 359° 85% 15% 92% 28%

Burgundy #800020 50% 0% 13% 345° 100% 25% 100% 50%

Burlywood #DEB887 87% 72% 53% 34° 57% 70% 39% 87%

Burnt orange #CC5500 80% 33% 0% 25° 100% 40% 100% 80%

Burnt sienna #E97451 91% 45% 32% 14° 78% 62% 65% 91%

Burnt umber #8A3324 54% 20% 14% 9° 59% 34% 74% 54%

Byzantine #BD33A4 74% 20% 64% 311° 57% 47% 73% 74%

Byzantium #702963 44% 16% 39% 311° 46% 30% 63% 44%

C

Color names

Name Hex triplet Red Green Blue Hue Satur Light Satur Value W3C name

Cadet #536872 33% 41% 47% 206° 18% 40% 31% 47%

Cadet blue #5F9EA0 37% 62% 63% 182° 26% 50% 41% 63%

Cadet grey #91A3B0 57% 64% 69% 205° 16% 63% 18% 69%

Cadmium green #006B3C 0% 42% 24% 154° 100% 21% 100% 42%

Cadmium orange #ED872D 93% 53% 18% 28° 84% 55% 81% 93%

Cadmium red #E30022 89% 0% 13% 351° 100% 45% 100% 89%

Cadmium yellow #FFF600 100% 96% 0% 34° 100% 50% 93% 100%

Café au lait #A67B5B 65% 48% 36% 26° 30% 50% 45% 65%

Café noir #4B3621 29% 21% 13% 30° 39% 21% 56% 29%

Cal Poly Pomona green #1E4D2B 12% 30% 17% 137° 44% 21% 61% 30%

Cambridge Blue #A3C1AD 64% 76% 68% 99° 20% 70% 40% 193%

Camel #C19A6B 76% 60% 42% 33° 41% 59% 45% 76%

Camouflage green #78866B 47% 53% 42% 91° 11% 47% 20% 53%

Canary yellow #FFEF00 100% 94% 0% 56° 100% 50% 100% 100%

Candy apple red #FF0800 100% 3% 0% 2° 100% 50% 100% 100%

Candy pink #E4717A 89% 44% 48% 355° 68% 67% 50% 89%

Capri #00BFFF 0% 75% 100% 195° 100% 50% 100% 100%

Caput mortuum #592720 35% 15% 13% 7° 47% 24% 64% 35%

Cardinal #C41E3A 77% 12% 23% 350° 74% 44% 85% 77%

List of colors 76

Caribbean green #00CC99 0% 80% 60% 150° 100% 40% 100% 44%

Carmine #FF0040 100% 0% 25% 0° 100% 50% 100% 50%

Carmine pink #EB4C42 92% 30% 26% 4° 81% 59% 72% 92%

Carmine red #FF0038 100% 0% 22% 347° 100% 50% 100% 100%

Carnation pink #FFA6C9 100% 65% 79% 336° 100% 83% 35% 100%

Carnelian #B31B1B 70% 11% 11% 0° 74% 40% 85% 70%

Carolina blue #99BADD 60% 73% 89% 211° 57% 75% 31% 87%

Carrot orange #ED9121 93% 57% 13% 33° 85% 53% 86% 93%

Celadon #ACE1AF 67% 88% 69% 123° 47% 78% 24% 88%

Celeste (colour) #B2FFFF 70% 100% 100% 180° 100% 85% 30% 100%

Celestial blue #4997D0 29% 59% 82% 205° 59% 55% 65% 81%

Cerise #DE3163 85% 20% 53% 330° 69% 53% 69% 72%

Cerise pink #EC3B83 93% 23% 59% 336° 82% 58% 75% 93%

Cerulean #007BA7 0% 48% 65% 196° 100% 33% 100% 65%

Cerulean blue #2A52BE 16% 32% 75% 224° 64% 46% 78% 75%

CG Blue #007AA5 0% 48% 65% 196° 100% 32% 100% 65%

CG Red #E03C31 88% 24% 19% 4° 74% 54% 78% 88%

Chamoisee #A0785A 63% 47% 35% 26° 28% 49% 44% 63%

Champagne #FAD6A5 98% 84% 65% 35° 90% 81% 34% 98%

Charcoal #36454F 21% 27% 31% 204° 19% 26% 31% 31%

Chartreuse (traditional) #DFFF00 87% 100% 0% 68° 100% 50% 100% 100%

Chartreuse (web) #7FFF00 50% 100% 0% 90° 100% 50% 100% 100%

Cherry #DE3163 87% 19% 39% 343° 72% 53% 78% 87%

Cherry blossom pink #FFB7C5 100% 72% 77% 348° 100% 86% 28% 100%

Chestnut #CD5C5C 80% 36% 36% 0° 53% 58% 55% 80%

Chocolate (traditional) #7B3F00 48% 25% 0% 31° 100% 24% 100% 48%

Chocolate (web) #D2691E 82% 41% 12% 25° 75% 47% 86% 82%

Chrome yellow #FFA700 100% 65% 0% 40° 100% 50% 100% 100%

Cinereous #98817B 60% 51% 48% 12° 12% 54% 19% 60%

Cinnabar #E34234 89% 26% 20% 5° 76% 55% 77% 89%

Cinnamon #D2691E 82% 41% 12% 25° 75% 47% 86% 82%

Citrine #E4D00A 89% 82% 4% 54° 92% 47% 96% 89%

Classic rose #FBCCE7 98% 80% 91% 333° 86% 89% 100% 20%

Cobalt #0047AB 0% 28% 67% 215° 100% 34% 100% 67%

Cocoa brown #D2691E 82% 41% 12% 25° 75% 47% 86% 82%

Coffee #6F4E37 44% 31% 22% 25° 34% 33% 51% 44%

Columbia blue #9BDDFF 61% 87% 100% 200° 100% 80% 39% 100%

Cool black #002E63 0% 18% 39% 212° 100% 19% 100% 39%

Cool grey #8C92AC 55% 57% 67% 229° 16% 61% 19% 68%

List of colors 77

Copper #B87333 72% 45% 20% 29° 57% 46% 72% 72%

Copper rose #996666 60% 40% 40% 0° 20% 50% 33% 60%

Coquelicot #FF3800 100% 22% 0% 13° 100% 50% 100% 100%

Coral #FF7F50 100% 50% 31% 16° 100% 66% 69% 100%

Coral pink #F88379 97% 51% 47% 5° 90% 72% 51% 97%

Coral red #FF4040 100% 25% 25% 0° 100% 63% 75% 100%

Cordovan #893F45 54% 25% 27% 337° 37% 39% 89% 94%

Corn #FBEC5D 98% 93% 36% 54° 95% 68% 63% 98%

Cornell Red #B31B1B 70% 11% 11% 0° 74% 40% 85% 70%

Cornflower blue #6495ED 39% 58% 93% 219° 79% 66% 58% 93%

Cornsilk #FFF8DC 100% 97% 86% 48° 100% 93% 14% 100%

Cosmic latte #FFF8E7 100% 97% 91% 42° 100% 95% 9% 100%

Cotton candy #FFBCD9 100% 74% 85% 334° 100% 87% 26% 100%

Cream #FFFDD0 100% 99% 82% 57° 100% 91% 18% 100%

Crimson #DC143C 86% 8% 24% 348° 83% 47% 91% 86%

Crimson glory #BE0032 75% 0% 20% 356° 100% 37% 100% 75%

Cyan #00FFFF 0% 100% 100% 180° 100% 50% 100% 100% Cyan

Cyan (process) #00B7EB 0% 72% 92% 193° 100% 46% 100% 92%

D

Color names

Name Hex triplet Red Green Blue Hue Satur Light Satur Value W3C name

Daffodil #FFFF31 100% 100% 19% 60° 100% 60% 81% 100%

Dandelion #F0E130 94% 88% 19% 55° 87% 56% 80% 94%

Dark blue #00008B 0% 0% 55% 240° 100% 27% 100% 55%

Dark brown #654321 40% 26% 13% 30° 51% 26% 67% 40%

Dark byzantium #5D3954 36% 22% 33% 315° 24% 29% 39% 37%

Dark candy apple red #A40000 64% 0% 0% 0° 100% 32% 100% 64%

Dark cerulean #08457E 3% 27% 49% 209° 88% 26% 94% 49%

Dark chestnut #986960 60% 41% 38% 10° 23% 49% 37% 60%

Dark coral #CD5B45 80% 36% 27% 10° 58% 54% 66% 80%

Dark cyan #008B8B 0% 55% 55% 180° 100% 27% 24% 100%

Dark electric blue #536878 33% 41% 47% 180° 18% 40% 20% 25%

Dark goldenrod #B8860B 72% 53% 4% 43° 89% 38% 94% 72%

Dark gray #A9A9A9 66% 66% 66% 0° 0% 66% 0% 66%

Dark green #013220 0% 20% 13% 158° 96% 10% 98% 20%

Dark jungle green #1A2421 10% 14% 13% 120° 16% 12% 10% 10%

Dark khaki #BDB76B 74% 72% 42% 56° 38% 58% 43% 74%

List of colors 78

Dark lava #483C32 28% 24% 20% 27° 18% 24% 31% 28%

Dark lavender #734F96 45% 31% 59% 270° 31% 45% 47% 59%

Dark magenta #8B008B 55% 0% 55% 300° 100% 27% 100% 55%

Dark midnight blue #003366 0% 20% 40% 210° 100% 20% 100% 40%

Dark olive green #556B2F 33% 42% 18% 82° 39% 30% 56% 42%

Dark orange #FF8C00 100% 55% 0% 34° 100% 50% 100% 94%

Dark orchid #9932CC 60% 20% 80% 280° 61% 50% 75% 80%

Dark pastel blue #779ECB 47% 62% 80% 212° 45% 63% 41% 80%

Dark pastel green #03C03C 1% 75% 24% 138° 97% 38% 98% 75%

Dark pastel purple #966FD6 59% 44% 84% 263° 56% 64% 48% 84%

Dark pastel red #C23B22 76% 23% 13% 9° 70% 45% 82% 76%

Dark pink #E75480 91% 33% 50% 342° 75% 62% 64% 91%

Dark powder blue #003399 0% 20% 60% 220° 100% 30% 70% 60%

Dark raspberry #872657 53% 15% 34% 330° 56% 34% 72% 53%

Dark red #8B0000 55% 0% 0% 0° 100% 27% 100% 56%

Dark salmon #E9967A 91% 59% 48% 15° 72% 70% 48% 91%

Dark scarlet #560319 34% 1% 10% 344° 93% 18% 97% 34%

Dark sea green #8FBC8F 56% 74% 56% 120° 25% 65% 24% 74%

Dark sienna #3C1414 24% 8% 8% 0° 50% 16% 67% 24%

Dark slate blue #483D8B 28% 24% 55% 248° 39% 39% 56% 55%

Dark slate gray #2F4F4F 18% 31% 31% 180° 25% 25% 41% 31%

Dark spring green #177245 9% 45% 27% 150° 66% 27% 80% 45%

Dark tan #918151 57% 51% 32% 45° 28% 44% 44% 57%

Dark tangerine #FFA812 100% 66% 7% 38° 100% 54% 93% 100%

Dark taupe #483C32 28% 24% 20% 30° 18% 24% 17% 34%

Dark terra cotta #CC4E5C 80% 31% 36% 354° 55% 55% 55% 55%

Dark turquoise #00CED1 0% 81% 82% 181° 100% 41% 100% 82%

Dark violet #9400D3 58% 0% 83% 282° 100% 41% 100% 83%

Dartmouth green #00693E 5% 50% 6% 121° 82% 28% 90% 50%

Davy's grey #555555 33% 33% 33% 0° 0% 33% 0% 33%

Debian red #D70A53 84% 4% 33% 339° 91% 44% 95% 84%

Deep carmine #A9203E 66% 13% 24% 357° 68% 39% 100% 66%

Deep carmine pink #EF3038 94% 19% 22% 357° 86% 56% 80% 94%

Deep carrot orange #E9692C 91% 41% 17% 34° 81% 54% 76% 84%

Deep cerise #DA3287 85% 20% 53% 330° 69% 53% 77% 85%

Deep champagne #FAD6A5 98% 84% 65% 35° 90% 81% 34% 98%

Deep chestnut #B94E48 73% 31% 28% 3° 45% 50% 61% 73%

Deep coffee #704241 44% 26% 25% 1° 27% 35% 42% 44%

Deep fuchsia #C154C1 76% 33% 76% 300° 47% 54% 56% 76%

List of colors 79

Deep jungle green #004B49 0% 29% 29% 120° 100% 15% 40% 40%

Deep lilac #9955BB 60% 33% 73% 280° 43% 53% 55% 73%

Deep magenta #CC00CC 80% 0% 80% 300° 100% 40% 100% 80%

Deep peach #FFCBA4 100% 80% 64% 26° 100% 82% 36% 100%

Deep pink #FF1493 100% 8% 58% 328° 100% 54% 92% 100%

Deep saffron #FF9933 100% 60% 20% 30° 100% 60% 80% 100%

Deep sky blue #00BFFF 0% 75% 100% 195° 100% 50% 100% 100%

Denim #1560BD 8% 38% 74% 213° 80% 41% 89% 74%

Desert #C19A6B 76% 60% 42% 33° 41% 59% 44% 76%

Desert sand #EDC9AF 93% 79% 69% 25° 63% 81% 26% 93%

Dim gray #696969 41% 41% 41% — 0% 41% 0% 41%

Dodger blue #1E90FF 12% 56% 100% 210° 100% 56% 88% 100%

Dogwood rose #D71868 84% 9% 41% 330° 80% 47% 84% 82%

Dollar bill #85BB65 52% 73% 40% 98° 39% 56% 46% 73%

Drab #967117 59% 44% 9% 43° 73% 34% 85% 59%

Duke blue #00009C 0% 0% 61% 240° 100% 31% 100% 61%

E

Color names

Name Hex triplet Red Green Blue Hue Satur Light Satur Value W3C name

Earth yellow #E1A95F 88% 66% 37% 34° 68% 63% 58% 88%

Ecru #C2B280 76% 70% 50% 45° 35% 63% 34% 76%

Eggplant #614051 38% 25% 32% 329° 21% 32% 34% 38%

Eggshell #F0EAD6 94% 92% 84% 46° 46% 89% 11% 94%

Egyptian blue #1034A6 6% 20% 65% 226° 82% 36% 90% 65%

Electric blue #7DF9FF 49% 98% 100% 183° 100% 75% 51% 100%

Electric crimson #FF003F 100% 0% 25% 345° 100% 50% 100% 100%

Electric cyan #00FFFF 0% 100% 100% 180° 100% 50% 100% 100%

Electric green #00FF00 0% 100% 0% 120° 100% 50% 100% 100%

Electric indigo #6F00FF 44% 0% 100% 266° 100% 50% 100% 100%

Electric lavender #F4BBFF 96% 73% 100% 290° 100% 87% 27% 100%

Electric lime #CCFF00 80% 100% 0% 72° 100% 50% 100% 100%

Electric purple #BF00FF 75% 0% 100% 285° 100% 50% 100% 100%

Electric ultramarine #3F00FF 25% 0% 100% 255° 100% 50% 100% 100%

Electric violet #8F00FF 56% 0% 100% 274° 100% 50% 100% 100%

Electric yellow #FFFF00 100% 100% 0% 60° 100% 50% 100% 100%

Emerald #50C878 31% 78% 47% 140° 52% 55% 60% 78%

Eton blue #96C8A2 59% 78% 64% 134° 31% 69% 25% 78%

List of colors 80

F

Color names

Name Hex triplet Red Green Blue Hue Satur Light Satur Value W3C name

Fallow #C19A6B 76% 60% 42% 45° 41% 59% 17% 23%

Falu red #801818 50% 9% 9% 0° 68% 30% 81% 50%

Famous #FF00FF 100% 0% 100% 300° 100% 50% 100% 100%

Fandango #B53389 71% 20% 54% 320° 56% 46% 72% 71%

Fashion fuchsia #F400A1 96% 0% 63% 320° 100% 48% 100% 96%

Fawn #E5AA70 90% 67% 44% 30° 69% 67% 51% 90%

Feldgrau #4D5D53 30% 36% 33% 142° 9% 33% 17% 36%

Fern green #4F7942 31% 47% 26% 106° 29% 37% 45% 47%

Ferrari Red #FF2800 100% 11% 0% 9° 100% 50% 100% 100%

Field drab #6C541E 42% 33% 12% 42° 56% 27% 72% 42%

Firebrick #B22222 70% 13% 13% 0° 68% 42% 81% 70%

Fire engine red #CE2029 81% 9% 13% 0° 81% 45% 92% 80%

Flame #E25822 89% 35% 13% 17° 77% 51% 85% 89%

Flamingo pink #FC8EAC 99% 56% 67% 344° 95% 77% 44% 99%

Flavescent #F7E98E 97% 91% 56% 52° 87% 76% 41% 76%

Flax #EEDC82 93% 86% 51% 50° 76% 72% 45% 93%

Floral white #FFFAF0 100% 98% 94% 40° 100% 97% 6% 100%

Fluorescent orange #FFBF00 100% 75% 0% 45° 100% 50% 100% 100%

Fluorescent pink #FF1493 100% 8% 58% 328° 100% 54% 92% 100%

Fluorescent yellow #CCFF00 80% 100% 0% 72° 100% 50% 100% 100%

Folly #FF004F 100% 0% 31% 341° 100% 50% 100% 100%

Forest green (traditional) #014421 0% 27% 13% 149° 97% 14% 99% 27%

Forest green (web) #228B22 13% 55% 13% 120° 61% 34% 76% 55%

French beige #A67B5B 65% 48% 36% 26° 30% 50% 45% 65%

French blue #0072BB 0% 45% 73% 203° 100% 37% 100% 73%

French lilac #86608E 53% 38% 56% 290° 19% 47% 32% 56%

French rose #F64A8A 96% 29% 54% 338° 91% 63% 70% 96%

Fuchsia #FF00FF 96% 0% 63% 321° 100% 48% 100% 100% Fuchsia

Fuchsia pink #FF77FF 100% 47% 88% 313° 100% 73% 53% 100%

Fulvous #E48400 86% 52% 0% 35° 100% 43% 100% 89%

Fuzzy Wuzzy #CC6666 80% 40% 40% 0° 50% 60% 50% 80%

List of colors 81

G

Color names

Name Hex triplet Red Green Blue Hue Satur Light Satur Value W3C name

Gainsboro #DCDCDC 86% 86% 86% — 0% 86% 0% 86%

Gamboge #E49B0F 89% 61% 6% 38° 88% 48% 94% 94%

Ghost white #F8F8FF 97% 97% 100% 24° 100% 99% 3% 100%

Ginger #B06500 69% 40% 0% 24° 100% 35% 255% 88%

Glaucous #6082B6 38% 51% 71% 216° 37% 55% 47% 71%

Glitter #E6E8FA 90% 91% 98% 234° 67% 94% 8% 98%

Gold (metallic) #D4AF37 83% 69% 22% 46° 65% 52% 74% 83%

Gold (web) (Golden) #FFD700 100% 84% 0% 51° 100% 50% 100% 100% Gold

Golden brown #996515 60% 40% 8% 36° 76% 34% 83% 60%

Golden poppy #FCC200 99% 76% 0% 46° 100% 49% 100% 99%

Golden yellow #FFDF00 100% 87% 0% 52° 100% 50% 100% 100%

Goldenrod #DAA520 85% 65% 13% 43° 74% 49% 85% 85%

Granny Smith Apple #A8E4A0 66% 89% 63% 113° 56% 76% 30% 89%

Gray #808080 50% 50% 50% — 0% 50% 0% 50% Grey

Gray (HTML/CSS gray) #7F7F7F 50% 50% 50% — 0% 50% 0% 50%

Gray (X11 gray) #BEBEBE 75% 75% 75% — 0% 75% 0% 75%

Gray-asparagus #465945 27% 35% 27% 117° 13% 31% 22% 35%

Green (color wheel) (X11 green) #00FF00 0% 100% 0% 120° 100% 50% 100% 100% Lime

Green (HTML/CSS green) #008000 0% 50% 0% 120° 100% 25% 100% 50% Green

Green (Munsell) #00A877 0% 66% 47% 163° 100% 33% 100% 66%

Green (NCS) #009F6B 0% 62% 42% 160° 100% 31% 100% 62%

Green (pigment) #00A550 0% 65% 31% 149° 100% 32% 100% 65%

Green (RYB) #66B032 40% 69% 20% 95° 56% 44% 72% 69%

Green-yellow #ADFF2F 68% 100% 18% 84° 100% 59% 82% 100%

Grullo #A99A86 66% 60% 53% 34° 17% 59% 21% 66%

Guppie green #00FF7F 0% 100% 50% 150° 100% 50% 100% 100%

H

List of colors 82

Color names

Name Hex triplet Red Green Blue Hue Satur Light Satur Value W3C name

Halayà úbe #663854 40% 22% 33% 278° 30% 31% 12% 37%

Han blue #446CCF 27% 42% 81% 223° 59% 54% 67% 81%

Han purple #5218FA 32% 9% 98% 255° 96% 54% 90% 98%

Hansa yellow #E9D66B 91% 84% 42% 51° 74% 67% 54% 91%

Harlequin #3FFF00 25% 100% 0% 105° 100% 50% 100% 100%

Harvard crimson #C90016 79% 0% 9% 353° 100% 39% 100% 79%

Harvest Gold #DA9100 85% 57% 0% 40° 100% 43% 100% 86%

Heart Gold #808000 50% 50% 0% 43° 100% 25% 100% 25%

Heliotrope #DF73FF 87% 45% 100% 286° 100% 73% 55% 100%

Hollywood cerise #F400A1 96% 0% 63% 320° 100% 48% 100% 96%

Honeydew #F0FFF0 94% 100% 94% 150° 100% 97% 97% 97%

Hooker's green #49796B 29% 47% 42% 163° 25% 38% 40% 48%

Hot magenta #FF1DCE 100% 11% 81% 313° 100% 56% 89% 100%

Hot pink #FF69B4 100% 41% 71% 330° 100% 71% 59% 100%

Hunter green #355E3B 21% 37% 23% 129° 28% 29% 44% 37%

I

Color names

Name Hex triplet Red Green Blue Hue Satur Light Satur Value W3C name

Icterine #FCF75E 99% 97% 37% 58° 96% 68% 63% 99%

Inchworm #B2EC5D 70% 93% 36% 84° 79% 65% 61% 93%

India green #138808 7% 53% 3% 115° 89% 28% 94% 53%

Indian red #CD5C5C 80% 36% 36% 0° 53% 58% 55% 80%

Indian yellow #E3A857 89% 66% 34% 35° 71% 62% 62% 89%

Indigo #4B0082 29% 0% 100% 260° 100% 50% 100% 100%

Indigo (dye) #00416A 0% 25% 42% 203° 100% 21% 100% 42%

Indigo (web) #4B0082 29% 0% 51% 275° 100% 26% 100% 50%

International Klein Blue #002FA7 0% 18% 65% 223° 100% 33% 100% 65%

International orange #FF4F00 100% 31% 0% 19° 100% 50% 100% 100%

Iris #5A4FCF 35% 31% 81% 245° 57% 56% 62% 81%

Isabelline #F4F0EC 96% 94% 93% 30° 27% 94% 3% 96%

Islamic green #009000 0% 56% 0% 120° 100% 28% 100% 56%

Ivory #FFFFF0 100% 100% 94% 60° 100% 97% 6% 100%

List of colors 83

J

Color names

Name Hex triplet Red Green Blue Hue Satur Light Satur Value W3C name

Jade #00A86B 0% 66% 42% 158° 100% 33% 100% 66%

Jasmine #F8DE7E 97% 87% 49% 47° 90% 73% 49% 97%

Jasper #D73B3E 84% 23% 24% 359° 66% 54% 73% 84%

Jazzberry jam #A50B5E 65% 4% 37% 322° 88% 35% 90% 47%

Jonquil #FADA5E 98% 85% 37% 48° 94% 68% 62% 98%

June bud #BDDA57 74% 85% 34% 80° 64% 60% 75% 85%

Jungle green #29AB87 16% 67% 53% 163° 61% 42% 76% 67%

K

Color names

Name Hex triplet Red Green Blue Hue Satur Light Satur Value W3C name

Kelly green #4CBB17 30% 73% 9% 101° 78% 41% 88% 73%

Khaki (HTML/CSS) (Khaki) #C3B091 76% 69% 57% 37° 29% 67% 26% 76%

Khaki (X11) (Light khaki) #F0E68C 94% 90% 55% 54° 77% 75% 42% 94%

KU Crimson #E8000D 91% 0% 5% 357° 100% 46% 100% 91%

L

Color names

Name Hex triplet Red Green Blue Hue Satur Light Satur Value W3C name

La Salle Green #087830 3% 47% 19% 141° 88% 25% 93% 47%

Languid lavender #D6CADD 84% 79% 87% 270° 22% 83% 17% 82%

Lapis lazuli #26619C 15% 38% 61% 210° 61% 38% 76% 61%

Laser Lemon #FEFE22 100% 100% 13% 60° 99% 56% 86% 57%

Laurel green #A9BA9D 66% 73% 62% 95° 17% 67% 16% 73%

Lava #CF1020 81% 6% 13% 355° 86% 44% 92% 81%

Lavender (floral) #B57EDC 71% 49% 86% 275° 57% 68% 43% 86%

Lavender (web) #E6E6FA 90% 90% 98% 245° 67% 94% 8% 98%

Lavender blue #CCCCFF 80% 80% 100% 240° 100% 90% 20% 100%

Lavender blush #FFF0F5 100% 94% 96% 340° 100% 97% 6% 100%

Lavender gray #C4C3D0 77% 76% 82% 245° 12% 79% 6% 82%

Lavender indigo #9457EB 58% 34% 92% 265° 79% 63% 63% 92%

List of colors 84

Lavender magenta #EE82EE 93% 51% 93% 300° 76% 72% 45% 93%

Lavender mist #E6E6FA 90% 90% 98% 240° 67% 94% 8% 98%

Lavender pink #FBAED2 98% 68% 82% 332° 91% 83% 31% 98%

Lavender purple #967BB6 59% 48% 71% 267° 29% 60% 32% 71%

Lavender rose #FBA0E3 98% 63% 89% 316° 92% 81% 36% 98%

Lawn green #7CFC00 49% 99% 0% 90° 100% 49% 98% 48%

Lemon #FFF700 100% 97% 0% 58° 100% 50% 100% 100%

Lemon chiffon #FFFACD 100% 98% 80% 54° 100% 90% 20% 100%

Lemon lime #BFFF00 89% 100% 0% 44° 100% 50% 240% 100%

Light apricot #FDD5B1 99% 84% 69% 30° 95% 84% 22% 89%

Light blue #ADD8E6 68% 85% 90% 194° 53% 79% 24% 90%

Light brown #B5651D 71% 40% 11% 28° 72% 41% 84% 71%

Light carmine pink #E66771 90% 40% 38% 350° 73% 64% 70% 80%

Light coral #F08080 94% 50% 50% 0° 79% 72% 50% 100%

Light cornflower blue #93CCEA 60% 81% 93% 201° 68% 77% 37% 92%

Light Crimson #F56991 96% 41% 57% 343° 88% 69% 57% 96%

Light cyan #E0FFFF 88% 100% 100% 180° 100% 94% 12% 100%

Light fuchsia pink #F984EF 98% 52% 94% 300° 91% 75% 27% 94%

Light goldenrod yellow #FAFAD2 98% 98% 82% 60° 80% 90% 16% 98%

Light gray #D3D3D3 83% 83% 83% — 0% 83% 0% 83%

Light green #90EE90 56% 93% 56% 120° 73% 75% 39% 93%

Light khaki #F0E68C 94% 90% 55% 54° 77% 75% 42% 94%

Light pastel purple #B19CD9 69% 61% 85% 261° 45% 73% 28% 85%

Light pink #FFB6C1 100% 71% 76% 351° 100% 86% 100% 86%

Light salmon #FFA07A 100% 63% 48% 14° 100% 74% 62% 100%

Light salmon pink #FF9999 100% 60% 60% 0° 100% 80% 40% 100%

Light sea green #20B2AA 13% 70% 67% 175° 70% 41% 40% 75%

Light sky blue #87CEFA 53% 81% 98% 203° 92% 76% 46% 98%

Light slate gray #778899 47% 53% 60% 210° 14% 53% 22% 60%

Light taupe #B38B6D 70% 55% 43% 26° 32% 56% 39% 70%

Light Thulian pink #E68FAC 90% 56% 67% 330° 64% 73% 72% 94%

Light yellow #FFFFED 100% 100% 88% 60° 100% 94% 7% 100%

Lilac #C8A2C8 78% 64% 78% 300° 26% 71% 19% 78%

Lime (color wheel) #BFFF00 75% 100% 0% 75° 100% 50% 100% 100%

Lime (web) (X11 green) #00FF00 0% 100% 0% 120° 100% 50% 100% 100% Lime

Lime green #32CD32 20% 80% 20% 120° 61% 50% 67% 40%

Lincoln green #195905 11% 35% 2% 106° 89% 18% 94% 35%

Linen #FAF0E6 98% 94% 90% 30° 67% 94% 8% 98%

Lion #C19A6B 76% 60% 42% 33° 41% 59% 45% 76%

List of colors 85

Liver #534B4F 33% 29% 31% 330° 5% 31% 10% 33%

Lust #E62020 90% 13% 13% 0° 80% 51% 86% 90%

M

Color names

Name Hex triplet Red Green Blue Hue Satur Light Satur Value W3C name

Magenta #FF00FF 78% 0% 40% 328° 100% 39% 100% 100% Fuchsia

Magenta (dye) #CA1F7B 79% 8% 48% 326° 81% 44% 90% 79%

Magenta (process) #FF0090 100% 0% 56% 326° 100% 50% 100% 100%

Magic mint #AAF0D1 67% 94% 82% 150° 70% 80% 84% 80%

Magnolia #F8F4FF 97% 96% 100% 247° 100% 98% 94% 92%

Mahogany #C04000 75% 25% 0% 20° 100% 38% 100% 75%

Maize #FBEC5D 98% 93% 37% 54° 95% 68% 63% 98%

Majorelle Blue #6050DC 38% 31% 86% 247° 67% 59% 67% 59%

Malachite #0BDA51 4% 85% 32% 140° 90% 45% 95% 85%

Manatee #979AAA 59% 60% 67% 231° 10% 63% 11% 67%

Mango Tango #FF8243 100% 51% 26% 20° 100% 63% 74% 100%

Mantis #74C365 45% 76% 40% 110° 44% 58% 48% 77%

Maroon (HTML/CSS) #800000 50% 0% 0% 0° 100% 25% 100% 50% Maroon

Maroon (X11) #B03060 69% 19% 38% 333° 57% 44% 65% 42%

Mauve #E0B0FF 88% 69% 100% 276° 100% 85% 31% 100%

Mauve taupe #915F6D 57% 37% 43% 285° 21% 47% 37% 54%

Mauvelous #EF98AA 94% 60% 67% 348° 73% 77% 37% 94%

Maya blue #73C2FB 45% 76% 98% 210° 94% 72% 96% 87%

Meat brown #E5B73B 90% 72% 23% 44° 77% 56% 74% 90%

Medium aquamarine #66DDAA 40% 80% 67% 154° 51% 60% 54% 87%

Medium blue #0000CD 0% 0% 80% 240° 100% 40% 100% 80%

Medium candy apple red #E2062C 89% 2% 17% 350° 95% 46% 97% 89%

Medium carmine #AF4035 69% 25% 21% 5° 54% 45% 69% 68%

Medium champagne #F3E5AB 95% 90% 67% 48° 75% 81% 30% 95%

Medium electric blue #035096 1% 31% 59% 180° 96% 30% 30% 60%

Medium jungle green #1C352D 11% 21% 18% 120° 31% 16% 20% 20%

Medium lavender magenta #DDA0DD 80% 60% 80% 300° 33% 70% 28% 87%

Medium orchid #BA55D3 73% 33% 83% 288° 59% 58% 60% 83%

Medium Persian blue #0067A5 0% 40% 65% 248° 100% 32% 75% 48%

Medium purple #9370DB 58% 44% 86% 270° 60% 65% 68% 72%

Medium red-violet #BB3385 73% 20% 52% 322° 57% 47% 79% 83%

Medium sea green #3CB371 24% 70% 44% 150° 50% 47% 42% 30%

List of colors 86

Medium slate blue #7B68EE 48% 41% 93% 249° 80% 67% 56% 93%

Medium spring bud #C9DC87 79% 86% 54% 80° 54% 70% 70% 80%

Medium spring green #00FA9A 0% 98% 60% 150° 100% 49% 97% 97%

Medium taupe #674C47 40% 30% 28% 9° 18% 34% 31% 40%

Medium teal blue #0054B4 0% 33% 71% 212° 100% 35% 100% 71%

Medium turquoise #48D1CC 28% 82% 80% 175° 60% 55% 55% 50%

Medium violet-red #C71585 78% 8% 52% 322° 81% 43% 89% 78%

Melon #FDBCB4 99% 74% 71% 7° 95% 85% 29% 99%

Midnight blue #191970 10% 10% 44% 240° 64% 27% 78% 44%

Midnight green (eagle green) #004953 0% 29% 33% 187° 100% 16% 100% 33%

Mikado yellow #FFC40C 100% 77% 5% 45° 100% 52% 95% 100%

Mint #3EB489 24% 71% 54% 158° 49% 48% 66% 71%

Mint cream #F5FFFA 96% 100% 98% 150° 100% 98% 4% 100%

Mint green #98FF98 60% 100% 60% 140° 100% 80% 40% 100%

Misty rose #FFE4E1 100% 89% 88% 337° 100% 94% 37% 94%

Moccasin #FAEBD7 98% 92% 84% 34° 78% 91% 14% 98%

Mode beige #967117 59% 44% 9% 43° 73% 34% 85% 59%

Moonstone blue #73A9C2 45% 66% 76% 199° 39% 61% 41% 76%

Mordant red 19 #AE0C00 68% 5% 0% 4° 100% 34% 100% 68%

Moss green #ADDFAD 68% 87% 68% 120° 44% 78% 22% 87%

Mountain Meadow #30BA8F 19% 73% 56% 161° 59% 46% 74% 73%

Mountbatten pink #997A8D 60% 48% 55% 323° 13% 54% 20% 60%

Mulberry #C54B8C 77% 29% 55% 285° 51% 53% 67% 70%

Munsell #F2F3F4 95% 95% 96% 210° 8% 95% 1% 96%

Mustard #FFDB58 100% 86% 35% 47° 100% 67% 65% 100%

Myrtle #21421E 13% 26% 12% 115° 38% 19% 54% 26%

MSU Green #18453B 9% 27% 23% 167° 48% 18% 65% 27%

N

Color names

Name Hex triplet Red Green Blue Hue Satur Light Satur Value W3C name

Nadeshiko pink #F6ADC6 96% 68% 78% 339° 80% 82% 30% 96%

Napier green #2A8000 16% 50% 0% 100° 100% 25% 100% 50%

Naples yellow #FADA5E 98% 85% 37% 48° 94% 68% 62% 98%

Navajo white #FFDEAD 100% 87% 68% 32° 100% 84% 27% 100%

Navy blue #000080 0% 0% 50% 240° 100% 25% 100% 50%

Neon Carrot #FFA343 100% 64% 26% 31° 100% 63% 74% 100%

Neon fuchsia #FE59C2 100% 25% 39% 322° 99% 63% 65% 100%

List of colors 87

Neon green #39FF14 22% 88% 8% 111° 84% 48% 92% 100%

Non-photo blue #A4DDED 64% 87% 93% 193° 67% 79% 31% 93%

North Texas Green [3] #059033 2% 56% 20% 140° 93% 29% 97% 56%

O

Color names

Name Hex triplet Red Green Blue Hue Satur Light Satur Value W3C name

Ocean Boat Blue #0077BE 0% 47% 75% 30° 100% 37% 83% 80%

Ochre #CC7722 80% 47% 13% 30° 71% 47% 83% 80%

Office green #008000 0% 50% 0% 120° 100% 25% 80% 50% Green

Old gold #CFB53B 81% 71% 23% 49° 61% 52% 71% 81%

Old lace #FDF5E6 99% 96% 90% 40° 85% 95% 6% 100%

Old lavender #796878 47% 41% 47% 270° 8% 44% 3% 22%

Old mauve #673147 40% 19% 28% 336° 36% 30% 52% 40%

Old rose #C08081 75% 50% 51% 330° 34% 63% 59% 57%

Olive #808000 50% 50% 0% 60° 100% 25% 100% 50%

Olive Drab (web) (Olive Drab #3) #6B8E23 42% 56% 14% 80° 61% 35% 75% 56%

Olive Drab #7 #3C341F 24% 20% 12% 31° 32% 18% 81% 46%

Olivine #9AB973 60% 73% 45% 58° 33% 59% 80% 141%

Onyx #0F0F0F 6% 6% 6% 0° 0% 6% 0% 6%

Opera mauve #B784A7 72% 52% 65% 276° 26% 62% 20% 62%

Orange (Color Wheel) #FF7F00 100% 50% 0% 30° 100% 50% 100% 100%

Orange (RYB) #FB9902 98% 60% 1% 60° 98% 50% 100% 73%

Orange (web color) #FFA500 100% 65% 0% 39° 100% 50% 100% 100%

Orange peel #FF9F00 100% 62% 0% 38° 100% 50% 100% 100%

Orange-red #FF4500 100% 27% 0% 5° 100% 50% 100% 52%

Orchid #DA70D6 85% 44% 84% 302° 59% 65% 49% 85%

Otter brown #654321 40% 26% 13% 30° 51% 26% 67% 40%

Outer Space #414A4C 25% 29% 30% 191° 8% 28% 15% 30%

Outrageous Orange #FF6E4A 100% 43% 29% 12° 100% 65% 71% 100%

Oxford Blue #002147 0% 13% 28% 212° 100% 14% 100% 28%

OU Crimson Red #990000 60% 0% 0% 0° 100% 30% 100% 60%

List of colors 88

P

Color names

Name Hex triplet Red Green Blue Hue Satur Light Satur Value W3C name

Pakistan green #006600 0% 40% 0% 120° 100% 20% 100% 40%

Palatinate blue #273BE2 15% 23% 89% 224° 76% 52% 84% 77%

Palatinate purple #682860 41% 16% 38% 277° 44% 28% 47% 44%

Pale aqua #BCD4E6 74% 83% 90% 206° 46% 82% 18% 90%

Pale blue #AFEEEE 69% 93% 93% 180° 65% 81% 26% 93%

Pale brown #987654 60% 46% 33% 30° 29% 46% 45% 60%

Pale carmine #AF4035 69% 25% 21% 5° 54% 45% 69% 68%

Pale cerulean #9BC4E2 61% 77% 89% 205° 55% 75% 31% 89%

Pale chestnut #DDADAF 87% 68% 69% 358° 41% 77% 22% 87%

Pale copper #DA8A67 85% 54% 40% 18° 61% 63% 53% 85%

Pale cornflower blue #ABCDEF 67% 80% 94% 210° 68% 80% 28% 94%

Pale gold #E6BE8A 90% 75% 54% 50° 65% 72% 47% 82%

Pale goldenrod #EEE8AA 93% 91% 67% 55° 67% 80% 29% 93%

Pale green #98FB98 60% 98% 60% 120° 93% 79% 39% 98%

Pale lavender #DCD0FF 86% 82% 100% 255° 100% 91% 18% 100%

Pale magenta #F984E5 98% 52% 90% 310° 91% 75% 47% 98%

Pale pink #FADADD 98% 85% 87% 354° 76% 92% 13% 98%

Pale plum #DDA0DD 80% 60% 80% 300° 33% 70% 28% 87%

Pale red-violet #DB7093 86% 44% 58% 340° 60% 65% 49% 86%

Pale robin egg blue #96DED1 59% 87% 82% 169° 52% 73% 32% 87%

Pale silver #C9C0BB 79% 75% 73% 0° 12% 76% 0% 80%

Pale spring bud #ECEBBD 93% 92% 74% 80° 55% 83% 60% 90%

Pale taupe #BC987E 74% 60% 49% 25° 32% 62% 33% 74%

Pale violet-red #DB7093 86% 44% 58% 340° 60% 65% 49% 86%

Pansy purple #78184A 47% 9% 29% 287° 67% 28% 36% 27%

Papaya whip #FFEFD5 100% 94% 84% 37° 100% 92% 16% 100%

Paris Green #50C878 31% 78% 47% 140° 52% 55% 60% 78%

Pastel blue #AEC6CF 68% 78% 81% 196° 26% 75% 16% 81%

Pastel brown #836953 51% 41% 33% 28° 22% 42% 37% 51%

Pastel gray #CFCFC4 81% 81% 77% 60° 10% 79% 5% 81%

Pastel green #77DD77 47% 87% 47% 120° 60% 67% 46% 87%

Pastel magenta #F49AC2 96% 60% 76% 333° 80% 78% 37% 96%

Pastel orange #FFB347 100% 70% 28% 35° 100% 64% 72% 100%

Pastel pink #FFD1DC 100% 82% 86% 346° 100% 91% 18% 100%

Pastel purple #B39EB5 70% 62% 71% 295° 14% 67% 13% 71%

List of colors 89

Pastel red #FF6961 100% 41% 38% 3° 100% 69% 62% 100%

Pastel violet #CB99C9 80% 60% 79% 302° 33% 70% 25% 80%

Pastel yellow #FDFD96 99% 99% 59% 60° 96% 79% 41% 99%

Patriarch #800080 50% 0% 50% 300° 100% 25% 100% 50%

Payne's grey #536878 33% 41% 47% 206° 18% 40% 31% 47%

Peach #FFE5B4 100% 90% 71% 39° 100% 85% 29% 100%

Peach-orange #FFCC99 100% 80% 60% 30° 100% 80% 40% 100%

Peach puff #FFDAB9 100% 85% 73% 40° 100% 86% 29% 100%

Peach-yellow #FADFAD 98% 87% 68% 39° 89% 83% 31% 98%

Pear #D1E231 82% 89% 19% 66° 75% 54% 78% 89%

Pearl #EAE0C8 92% 88% 78% 42° 45% 85% 15% 92%

Pearl Aqua #88D8C0 53% 85% 75% 162° 51% 69% 37% 85%

Peridot #E6E200 90% 89% 0% 59° 100% 45% 100% 90%

Periwinkle #CCCCFF 80% 80% 100% 240° 100% 90% 20% 100%

Persian blue #1C39BB 11% 22% 73% 248° 74% 42% 75% 50%

Persian green #00A693 0% 65% 58% 135° 100% 33% 75% 60%

Persian indigo #32127A 20% 7% 48% 249° 74% 28% 85% 49%

Persian orange #D99058 85% 56% 35% 26° 63% 60% 59% 85%

Persian pink #F77FBE 97% 50% 75% 330° 88% 73% 72% 77%

Persian plum #701C1C 44% 11% 11% 0° 60% 28% 75% 44%

Persian red #CC3333 80% 20% 20% 5° 60% 50% 50% 50%

Persian rose #FE28A2 100% 16% 64% 318° 99% 58% 96% 88%

Phlox #DF00FF 87% 0% 100% 292° 100% 50% 100% 100%

Phthalo blue #000F89 0% 6% 54% 233° 100% 27% 100% 54%

Phthalo green #123524 7% 21% 14% 151° 49% 14% 66% 21%

Piggy pink #FDDDE6 99% 87% 90% 343° 89% 93% 13% 99%

Pine green #01796F 0% 47% 44% 175° 98% 24% 99% 47%

Pink #FFC0CB 100% 75% 80% 350° 100% 88% 25% 100%

Pink-orange #FF9966 100% 60% 40% 20° 100% 70% 60% 100%

Pink pearl #E7ACCF 91% 67% 81% 324° 55% 79% 26% 91%

Pink Sherbet #F78FA7 97% 56% 65% 346° 87% 77% 42% 97%

Pistachio #93C572 58% 77% 45% 96° 42% 61% 42% 77%

Platinum #E5E4E2 90% 89% 89% 40° 6% 89% 1% 90%

Plum (traditional) #8E4585 56% 27% 52% 307° 35% 41% 51% 56%

Plum (web) #DDA0DD 80% 60% 80% 300° 33% 70% 28% 87%

Portland Orange #FF5A36 100% 35% 21% 11° 100% 61% 79% 100%

Powder blue (web) #B0E0E6 69% 88% 90% 220° 52% 80% 70% 90%

Princeton orange #FF8F00 100% 56% 0% 34° 100% 50% 100% 100%

Prune #701C1C 44% 11% 11% 0° 60% 28% 75% 44%

List of colors 90

Prussian blue #003153 0% 19% 33% 205° 100% 16% 100% 33%

Psychedelic purple #DF00FF 87% 0% 100% 292° 100% 50% 100% 100%

Puce #CC8899 80% 53% 60% 345° 40% 67% 33% 80%

Pumpkin #FF7518 100% 46% 9% 24° 100% 55% 90% 100%

Purple (HTML/CSS) #800080 50% 0% 50% 300° 100% 25% 100% 50% Purple

Purple (Munsell) #9F00C5 62% 0% 77% 288° 100% 39% 100% 77%

Purple (X11) #A020F0 63% 36% 94% 285° 83% 65% 97% 77%

Purple Heart #69359C 41% 21% 61% 270° 49% 41% 66% 61%

Purple mountain majesty #9678B6 59% 47% 71% 260° 30% 59% 34% 71%

Purple pizzazz #FE4EDA 100% 31% 85% 312° 99% 65% 69% 100%

Purple taupe #50404D 31% 25% 30% 285° 11% 28% 19% 33%

Q

Color names

Name Hex triplet Red Green Blue Hue Satur Light Satur Value W3C name

Quartz #51484F 32% 28% 31% 345° 6% 30% 84% 84%

R

Color names

Name Hex triplet Red Green Blue Hue Satur Light Satur Value W3C name

Radical Red #FF355E 100% 21% 37% 345° 100% 60% 84% 84%

Rackley #5D8AA8 36% 54% 66% 204° 30% 51% 45% 66%

Raspberry #E30B5D 89% 4% 36% 337° 91% 47% 95% 89%

Raspberry glace #915F6D 57% 37% 43% 333° 21% 47% 35% 57%

Raspberry pink #E25098 89% 31% 61% 330° 72% 60% 65% 89%

Raspberry rose #B3446C 70% 27% 42% 38° 45% 48% 62% 70%

Raw umber #826644 51% 40% 27% 33° 31% 39% 48% 51%

Razzle dazzle rose #FF33CC 100% 20% 80% 312° 100% 60% 51% 204%

Razzmatazz #E3256B 89% 15% 42% 338° 77% 52% 84% 89%

Red #FF0000 100% 0% 0% 0° 100% 50% 100% 100% Red

Red (Munsell) #F2003C 95% 0% 24% 345° 100% 48% 100% 95%

Red (NCS) #C40233 77% 1% 20% 358° 98% 39% 88% 93%

Red (pigment) #ED1C24 93% 11% 14% 0° 85% 52% 100% 65%

Red (RYB) #FE2712 100% 15% 7% 0° 99% 53% 100% 87%

Red-brown #A52A2A 65% 16% 16% 0° 59% 41% 75% 65%

Red-violet #C71585 78% 8% 52% 322° 81% 43% 89% 78%

List of colors 91

Redwood #AB4E52 67% 31% 32% 348° 37% 49% 54% 67%

Rich black #004040 0% 25% 25% 180° 100% 13% 100% 25%

Rich brilliant lavender #F1A7FE 95% 65% 100% 291° 98% 83% 34% 100%

Rich carmine #D70040 84% 0% 25% 356° 100% 42% 94% 44%

Rich electric blue #0892D0 3% 57% 82% 180° 93% 42% 35% 75%

Rich lavender #A76BCF 67% 38% 80% 270° 51% 59% 78% 47%

Rich lilac #B666D2 71% 40% 82% 284° 55% 61% 51% 82%

Rich maroon #B03060 69% 19% 38% 333° 57% 44% 65% 42%

Rifle green #414833 25% 28% 20% 80° 17% 24% 29% 28%

Robin egg blue #00CCCC 0% 80% 80% 180° 100% 40% 100% 80%

Rose #FF007F 100% 0% 50% 330° 100% 50% 100% 100%

Rose bonbon #F9429E 98% 26% 62% 330° 94% 62% 74% 98%

Rose ebony #674846 40% 30% 28% 340° 18% 34% 17% 20%

Rose gold #B76E79 72% 43% 47% 340° 34% 57% 32% 62%

Rose madder #E32636 89% 15% 21% 355° 77% 52% 83% 89%

Rose pink #FF66CC 100% 40% 80% 330° 100% 70% 77% 84%

Rose quartz #AA98A9 67% 60% 66% 330° 10% 63% 12% 50%

Rose taupe #905D5D 56% 36% 36% 330° 22% 47% 42% 46%

Rose vale #AB4E52 67% 31% 32% 348° 37% 49% 54% 67%

Rosewood #65000B 40% 0% 4% 333° 100% 20% 75% 7%

Rosso corsa #D40000 83% 0% 0% 0° 100% 42% 100% 83%

Rosy brown #BC8F8F 74% 56% 56% 359° 25% 65% 25% 63%

Royal azure #0038A8 0% 22% 66% 220° 100% 33% 100% 66%

Royal blue (traditional) #002366 0% 14% 40% 219° 100% 20% 100% 20%

Royal blue (web) #4169E1 25% 41% 88% 225° 73% 57% 71% 88%

Royal fuchsia #CA2C92 79% 17% 57% 290° 64% 48% 67% 44%

Royal purple #7851A9 47% 32% 66% 267° 35% 49% 52% 66%

Ruby #E0115F 88% 7% 37% 338° 86% 47% 100% 40%

Ruddy #FF0028 100% 0% 16% 351° 100% 50% 100% 100%

Ruddy brown #BB6528 73% 40% 16% 25° 65% 45% 79% 73%

Ruddy pink #E18E96 88% 56% 59% 354° 58% 72% 37% 88%

Rufous #A81C07 66% 11% 3% 8° 92% 34% 96% 66%

Russet #80461B 50% 27% 11% 25° 65% 30% 78% 50%

Rust #B7410E 72% 25% 5% 18° 86% 39% 92% 72%

List of colors 92

S

Color names

Name Hex triplet Red Green Blue Hue Satur Light Satur Value W3C name

Sacramento State green #00563F 0% 34% 25% 164° 100% 17% 100% 34%

Saddle brown #8B4513 55% 27% 7% 25° 76% 31% 86% 55%

Safety orange (blaze orange) #FF6700 100% 40% 0% 24° 100% 50% 100% 100%

Saffron #F4C430 96% 77% 19% 45° 90% 57% 80% 96%

St. Patrick's blue #23297A 14% 16% 48% 236° 55% 31% 0% 52%

Salmon #FF8C69 100% 55% 41% 14° 100% 71% 59% 100%

Salmon pink #FF91A4 100% 57% 64% 14° 100% 78% 62% 100%

Sand #C2B280 76% 70% 50% 45° 35% 63% 34% 76%

Sand dune #967117 59% 44% 9% 43° 73% 34% 85% 59%

Sandstorm #ECD540 93% 84% 25% 52° 82% 59% 73% 93%

Sandy brown #F4A460 96% 64% 38% 28° 87% 67% 61% 96%

Sandy taupe #967117 59% 44% 9% 43° 73% 34% 85% 59%

Sap green #507D2A 31% 49% 16% 93° 50% 33% 66% 49%

Sapphire #0F52BA 6% 32% 73% 216° 85% 39% 91% 73%

Satin sheen gold #CBA135 80% 63% 21% 49° 59% 50% 74% 76%

Scarlet #FF2400 100% 14% 0% 8° 100% 50% 100% 100%

Scarlet (Crayola) #FF2400 99% 5% 21% 350° 98% 52% 95% 99%

School bus yellow #FFD800 100% 85% 0% 51° 100% 50% 100% 100%

Screamin' Green #76FF7A 46% 100% 44% 122° 100% 72% 54% 100%

Sea blue #006994 0% 50% 100% 209° 100% 50% 100% 100%

Sea green #2E8B57 0% 100% 50% 146° 100% 50% 77% 55%

Seal brown #321414 20% 8% 8% 0° 43% 14% 60% 20%

Seashell #FFF5EE 100% 96% 93% 25° 100% 97% 7% 100%

Selective yellow #FFBA00 100% 73% 0% 44° 100% 50% 100% 100%

Sepia #704214 44% 26% 8% 30° 70% 26% 82% 44%

Shadow #8A795D 54% 47% 36% 37° 20% 45% 33% 54%

Shamrock green #009E60 0% 62% 38% 120° 100% 31% 91% 75%

Shocking pink #FC0FC0 99% 6% 75% 315° 98% 52% 94% 99%

Sienna #882D17 53% 18% 9% 12° 71% 31% 83% 53%

Silver #C0C0C0 75% 75% 75% 0° 0% 75% 0% 75% Silver

Sinopia #CB410B 80% 25% 4% 17° 90% 42% 95% 80%

Skobeloff #007474 0% 48% 45% 140° 100% 24% 97% 44%

Sky blue #87CEEB 53% 81% 92% 210° 71% 73% 67% 96%

Sky magenta #CF71AF 81% 44% 69% 304° 50% 63% 87% 54%

Slate blue #6A5ACD 42% 35% 80% 248° 54% 58% 56% 80%

List of colors 93

Slate gray #708090 44% 50% 56% 210° 13% 50% 22% 56%

Smalt (Dark powder blue) #003399 0% 20% 60% 200° 100% 30% 70% 60%

Smokey topaz #933D41 58% 25% 3% 357° 90% 30% 59% 58%

Smoky black #100C08 6% 5% 3% 30° 33% 5% 50% 6%

Snow #FFFAFA 100% 98% 98% 0° 100% 99% 1% 100%

Spiro Disco Ball #0FC0FC 6% 75% 99% 195° 98% 52% 94% 99%

Spring bud #A7FC00 65% 99% 0% 88° 100% 49% 90% 63%

Spring green #00FF7F 89% 92% 74% 150° 54% 83% 100% 100%

Steel blue #4682B4 27% 51% 71% 207° 44% 49% 61% 71%

Stil de grain yellow #FADA5E 98% 85% 37% 48° 94% 68% 62% 98%

Stizza #990000 60% 0% 0% 0° 100% 30% 100% 60%

Stormcloud #008080 31% 40% 42% 189° 15% 36% 14% 67%

Straw #E4D96F 89% 85% 44% 54° 68% 67% 51% 89%

Sunglow #FFCC33 100% 80% 20% 50° 100% 60% 99% 98%

Sunset #FAD6A5 98% 84% 65% 35° 90% 81% 34% 98%

T

Color names

Name Hex triplet Red Green Blue Hue Satur Light Satur Value W3C name

Tan #D2B48C 82% 71% 55% 34° 44% 69% 33% 82% Tan

Tangelo #F94D00 98% 30% 0% 23° 100% 49% 100% 90%

Tangerine #F28500 95% 52% 0% 33° 100% 48% 100% 95%

Tangerine yellow #FFCC00 100% 80% 0% 48° 100% 50% 100% 100%

Taupe #483C32 28% 24% 20% 30° 18% 24% 17% 34%

Taupe gray #8B8589 55% 52% 54% 30° 3% 53% 1% 60%

Tea green #D0F0C0 82% 94% 75% 100° 62% 85% 20% 94%

Tea rose (orange) #F88379 97% 51% 47% 5° 90% 72% 51% 97%

Tea rose (rose) #F4C2C2 96% 76% 76% 0° 69% 86% 20% 96%

Teal #008080 0% 50% 50% 180° 100% 25% 100% 50% Teal

Teal blue #367588 21% 46% 53% 194° 43% 37% 50% 53%

Teal green #006D5B 0% 51% 50% 179° 100% 26% 100% 47%

Tenné (Tawny) #CD5700 80% 34% 0% 25° 100% 40% 100% 80%

Terra cotta #E2725B 89% 45% 36% 10° 70% 62% 60% 89%

Thistle #D8BFD8 85% 75% 85% 300° 24% 80% 12% 85%

Thulian pink #DE6FA1 87% 44% 63% 330° 63% 65% 82% 92%

Tickle Me Pink #FC89AC 99% 54% 67% 342° 95% 76% 46% 99%

Tiffany Blue #0ABAB5 4% 73% 71% 178° 90% 38% 95% 73%

Tiger's eye #E08D3C 88% 55% 24% 30° 73% 56% 73% 88%

List of colors 94

Timberwolf #DBD7D2 86% 84% 82% 33° 11% 84% 4% 86%

Titanium yellow #EEE600 93% 90% 0% 58° 100% 47% 100% 93%

Tomato #FF6347 100% 39% 28% 15° 100% 64% 75% 50%

Toolbox #746CC0 45% 42% 75% 174° 40% 59% 102% 150%

Topaz #FFC87C 100% 78% 49% 345° 100% 74% 84% 84%

Tractor red #FD0E35 99% 5% 21% 350° 98% 52% 94% 99%

Trolley Grey #808080 50% 50% 50% — 0% 50% 0% 50%

Tropical rain forest #00755E 0% 46% 37% 120° 100% 23% 70% 60%

True Blue #0073CF 0% 45% 81% 207° 100% 41% 100% 81%

Tufts Blue #417DC1 28% 57% 81% 208° 58% 55% 70% 100%

Tumbleweed #DEAA88 87% 67% 53% 24° 57% 70% 39% 87%

Turkish rose #B57281 71% 45% 51% 340° 31% 58% 100% 25%

Turquoise #30D5C8 19% 84% 78% 175° 66% 51% 77% 84% Turquoise

Turquoise blue #00FFEF 0% 100% 94% 176° 100% 50% 100% 100%

Turquoise green #A0D6B4 63% 84% 71% 142° 40% 73% 25% 84%

Tuscan red #66424D 40% 26% 30% 342° 21% 33% 35% 40%

Twilight lavender #8A496B 54% 29% 42% 329° 31% 41% 47% 89%

Tyrian purple #66023C 40% 1% 24% 277° 96% 20% 67% 44%

U

Color names

Name Hex triplet Red Green Blue Hue Satur Light Satur Value W3C name

UA blue #0033AA 0% 20% 67% 222° 100% 33% 100% 67%

UA red #D9004C 85% 0% 30% 359° 100% 43% 100% 85%

Ube #8878C3 53% 47% 76% 253° 39% 62% 39% 77%

UCLA Blue #536895 33% 41% 58% 221° 28% 46% 44% 58%

UCLA Gold #FFB300 100% 70% 0% 42° 100% 50% 100% 100%

UFO Green #3CD070 24% 82% 44% 141° 61% 53% 71% 82%

Ultramarine #120A8F 7% 4% 56% 244° 87% 30% 93% 56%

Ultramarine blue #4166F5 25% 40% 96% 228° 90% 61% 74% 96%

Ultra pink #FF6FFF 100% 44% 100% 300° 100% 72% 48% 83%

Umber #635147 39% 32% 28% 21° 17% 33% 28% 39%

United Nations blue #5B92E5 36% 57% 90% 210° 73% 63% 60% 90%

University of California Gold #B78727 72% 53% 15% 40° 65% 44% 79% 72%

Unmellow Yellow #FFFF66 100% 100% 40% 60° 100% 70% 60% 100%

UP Forest green #014421 0% 27% 13% 149° 97% 14% 99% 27%

UP Maroon #7B1113 48% 7% 7% 359° 76% 28% 86% 48%

Upsdell red #AE2029 68% 9% 13% 356° 78% 38% 82% 68%

List of colors 95

Urobilin #E1AD21 88% 68% 13% 44° 76% 51% 85% 88%

USC Cardinal #990000 60% 0% 0% 0° 100% 30% 100% 60%

USC Gold #FFCC00 100% 80% 0% 48° 100% 50% 100% 100%

Utah Crimson #D3003F 83% 0% 25% 342° 100% 41% 100% 83%

V

Color names

Name Hex triplet Red Green Blue Hue Satur Light Satur Value W3C name

Vanilla #F3E5AB 95% 90% 67% 48° 75% 81% 30% 95%

Vegas gold #C5B358 77% 70% 35% 50° 48% 56% 55% 77%

Venetian red #C80815 78% 3% 8% 0° 92% 41% 84% 84%

Verdigris #43B3AE 26% 70% 68% 177° 46% 48% 63% 70%

Vermilion #E34234 89% 26% 20% 5° 76% 55% 77% 89%

Veronica #A020F0 63% 36% 94% 285° 83% 65% 97% 77%

Violet #8F00FF 56% 0% 100% 274° 100% 50% 100% 100%

Violet (color wheel) #7F00FF 50% 0% 100% 270° 100% 50% 100% 100%

Violet (RYB) #8601AF 53% 0% 69% 270° 99% 35% 100% 71%

Violet (web) #EE82EE 93% 51% 93% 300° 76% 72% 45% 93%

Viridian #40826D 25% 51% 43% 161° 34% 38% 51% 51%

Vivid auburn #922724 58% 15% 14% 7° 61% 36% 72% 52%

Vivid burgundy #9F1D35 62% 11% 21% 345° 69% 37% 55% 60%

Vivid cerise #DA1D81 85% 11% 51% 328° 77% 48% 87% 86%

Vivid tangerine #FFA089 100% 63% 54% 12° 100% 77% 46% 100%

Vivid violet #9F00FF 62% 0% 100% 277° 100% 50% 100% 100%

W

Color names

Name Hex triplet Red Green Blue Hue Satur Light Satur Value W3C name

Warm black #004242 0% 26% 26% 180° 100% 13% 100% 26%

Waterspout #00FFFF 64% 96% 98% 183° 88% 81% 87% 97%

Wenge #645452 39% 33% 32% 7° 10% 36% 18% 39%

Wheat #F5DEB3 96% 87% 70% 39° 77% 83% 26% 96%

White #FFFFFF 100% 100% 100% — 0% 100% 0% 100% White

White smoke #F5F5F5 96% 96% 96% — 0% 96% 0% 96%

Wild blue yonder #A2ADD0 64% 68% 82% 226° 33% 73% 22% 81%

Wild Strawberry #FF43A4 100% 26% 64% 329° 100% 63% 74% 100%

List of colors 96

Wild Watermelon #FC6C85 99% 42% 52% 350° 96% 71% 57% 99%

Wine #722F37 45% 18% 22% 353° 42% 32% 59% 45%

Wisteria #C9A0DC 79% 63% 86% 281° 46% 75% 27% 86%

X

Color names

Name Hex triplet Red Green Blue Hue Satur Light Satur Value W3C name

Xanadu #738678 45% 53% 47% 136° 8% 49% 14% 52%

Y

Color names

Name Hex triplet Red Green Blue Hue Satur Light Satur Value W3C name

Yale Blue #0F4D92 6% 30% 57% 212° 81% 32% 90% 57%

Yellow #FFFF00 100% 100% 0% 60° 100% 50% 100% 100% Yellow

Yellow (Munsell) #EFCC00 94% 80% 0% 50° 100% 47% 100% 100%

Yellow (NCS) #FFD300 100% 83% 0% 50° 100% 50% 100% 100%

Yellow (process) #FFEF00 100% 94% 0% 56° 100% 50% 100% 100%

Yellow (RYB) #FEFE33 100% 100% 20% 60° 99% 60% 80% 99%

Yellow-green #9ACD32 60% 80% 20% 80° 61% 50% 76% 80%

Yellow Orange #FFAE42 100% 68% 26% 34° 100% 63% 74% 100%

Z

Color names

Name Hex triplet Red Green Blue Hue Satur Light Satur Value W3C name

Zaffre #0014A8 0% 8% 66% 233° 100% 33% 100% 66%

Zinnwaldite brown #2C1608 17% 9% 3% 23° 69% 10% 82% 17%

List of colors 97

Colors by shade

WhiteWhite is a balanced combination of all the colors of the visible light spectrum, or of a pair of complementary colors,or of three or more colors, such as additive primary colors. It is a neutral or achromatic (without color) color, likeblack and gray.

PinkPink is a tint of red, created by adding some white.

RedRed is any of a number of similar colors evoked by light, consisting predominantly of the longest wavelengthsdiscernible by the human eye, in the wavelength range of roughly 625–750 nm. It is considered one of the additiveprimary colors.

OrangeOrange is the color in the visible spectrum between red and yellow with a wavelength around 585 – 620 nm. In theHSV color space, it has a hue of around 30°.

BrownBrown colors are dark or muted shades of reds, oranges, and yellows on the RGB and CMYK color schemes. Inpractice, browns are created by mixing two complementary colors from the RYB color scheme (combining all threeprimary colors). In theory, such combinations should produce black, but produce brown because mostcommercially-available blue pigments tend to be comparatively weaker; the stronger red and yellow colors prevail,thus creating the following tones.

YellowYellow is the color of light with wavelengths predominately in the range of roughly 570–580 nm. In the HSV colorspace, it has a hue of around 60°. It is considered one of the subtractive primary colors.

GrayAchromatic grays are colors between black and white with no hue. Chromatic grays are achromatic grays mixed withwarm hues such as orange (warm grays) or cool hues such as azure (cool grays). This gray color template includesboth achromatic and chromatic grays.

List of colors 98

GreenGreen is a color, the perception of which is evoked by light having a spectrum dominated by energy with awavelength of roughly 520–570 nm. It is considered one of the additive primary colors.

CyanCyan is any of the colors in the blue-green range of the visible spectrum, i.e., between approximately 520 and420 nm. It is considered one of the subtractive primary colors.

BlueBlue is a color, the perception of which is evoked by light having a spectrum dominated by energy with awavelength of roughly 440–490 nm. It is considered one of the additive primary colors.

VioletViolet is any of the colors the perception of which is evoked by light having a spectrum dominated by energy with awavelength of roughly 380–450 nm. Tones of violet tending towards the blue are called indigo. Purple colors arecolors that are various blends of violet light or blue light and red light.

Web colorsThese are the colors used by computer graphic designers for web page designing. These colors are displayed on themonitors of computers.

Fictional colors• Garrow  and Infra-White  – colors invented in the Nebulous episode "Madness is a Strange Colour". The first

color both colors affect the human mind in odd ways, either destroying or creating sanity. Professor Nebulousclaims that he discovered Infra-White by looking underneath and behind the visible spectrum.

• Fuligin – both a color and a textile having that color, associated with the Guild of Torturers in Gene Wolfe'sbook, The Shadow of the Torturer. The color is defined as "the color that is darker than black" and also as "thecolor of soot."

• Grue and bleen – colors that change after an arbitrary, but fixed time; coined by Charles Dodgson and used byphilosopher Nelson Goodman to illustrate what he calls "the new riddle of induction."

• Hooloovoo – a superintelligent shade of the color blue in The Hitchhiker's Guide to the Galaxy series by DouglasAdams.

• Octarine – the color of magic in the Discworld fantasy novels, described as resembling a fluorescentgreenish-yellow purple.

• Squant – a fourth primary color publicized by the experimental band Negativland in 1993.• Jale and Ulfire – new primary colors (shades of ultraviolet?) in A Voyage to Arcturus by David Lindsay.• The Colour Out of Space – a vaguely-described alien hue, from the story of that name by H. P. Lovecraft.• The colors tang and burn are colors in the infrared range seen by the albino mutant Olivia Presteign (whose

vision only functions in the infrared) in the 1956 science fiction novel The Stars My Destination by AlfredBester.[4]

• Htun is a color similar to black only seen by gnomes in the book Fairest by Gail Carson Levine.• Sangoire is a color of red 'so dark and saturated it [is] almost black', seen in the Kushiel's Legacy Series by

Jacqueline Carey.• Blellow is the name given to the color created by Reese of Malcolm in the Middle when he mixed blue and yellow

together. Otherwise known as green.

List of colors 99

• Celestewhite is a color invented by Carlos Argentino for his lengthy topographical poem intended to describe theentire world, in Jorge Luis Borges' The Aleph. It "actually suggests the sky, an element of utmost importance inthe landscape of the Down Under."

Footnotes[1] Raggett, Dave (8 April 2002). "Dave Raggett's Introduction to CSS" (http:/ / www. w3. org/ MarkUp/ Guide/ Style). World Wide Web

Consortium. . Retrieved 9 December 2010.[2] Viewing surround conditions, IPA.org (http:/ / www. ipa. org/ bulletin/ articles/ view_cond. php3)[3] http:/ / www. unt. edu/ identityguide/ web-electronic. htm[4] Boucher, Anthony, Editor A Treasury of Great Science Fiction Garden City, New York:1959—Doubleday Volume Two—The Stars My

Destination by Alfred Bester, Pages 361–522—Color reference Page 465

References• Frery, A. C.; Melo, C. A. S. & Fernandes, R. C. (13 October 2000). "Web-based Interactive Dynamics for Color

Models Learning" (http:/ / www3. interscience. wiley. com/ journal/ 73504470/ abstract). Color Research andApplication 25 (6): 435–441. doi:10.1002/1520-6378(200012)25:6<435::AID-COL8>3.0.CO;2-J. Retrieved2009-03-15.

External links• CSS Colour Chart (http:/ / colour. pro/ CSS-Colour-Chart. htm)

Web colorsWeb colors are colors used in designing web pages, and the methods for describing and specifying those colors.Hexadecimal color codes begin with a hash (#).[1] [2]

Authors of web pages have a variety of options available for specifying colors for elements of web documents.Colors may be specified as an RGB triplet in hexadecimal format (a hex triplet); they may also be specifiedaccording to their common English names in some cases. Often a color tool or other graphics software is used togenerate color values.The first versions of Mosaic and Netscape Navigator used the X11 color names as the basis for their color lists, asboth started as X Window System applications.[3]

Web colors have an unambiguous colorimetric definition, sRGB, which relates the chromaticities of a particularphosphor set, a given transfer curve, adaptive whitepoint, and viewing conditions.[4] These have been chosen to besimilar to many real-world monitors and viewing conditions, so that even without color management rendering isfairly close to the specified values. However, user agents vary in the fidelity with which they represent the specifiedcolors. More advanced user agents use color management to provide better color fidelity; this is particularlyimportant for Web-to-print applications.

Hex tripletA hex triplet is a six-digit, three-byte hexadecimal number used in HTML, CSS, SVG, and other computingapplications, to represent colors. The bytes represent the red, green and blue components of the color. One byterepresents a number in the range 00 to FF (in hexadecimal notation), or 0 to 255 in decimal notation. This representsthe least (0) to the most (255) intensity of each of the color components. Thus web colors specify colors in theTruecolor (24-bit RGB) color scheme. The hex triplet is formed by concatenating three bytes in hexadecimalnotation, in the following order:

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Byte 1: red value (color type red)Byte 2: green value (color type green)Byte 3: blue value (color type blue)

For example, consider the color where the red/green/blue values are decimal numbers: red=36, green=104, blue=160(a greyish-blue color). The decimal numbers 36, 104 and 160 are equivalent to the hexadecimal numbers 24, 68 andA0 respectively. The hex triplet is obtained by concatenating the 6 hexadecimal digits together, 2468A0 in thisexample.Note that if any one of the three color values is less than 16 (decimal) or 10 (hex), it must be represented with aleading zero so that the triplet always has exactly six digits. For example, the decimal triplet 4, 8, 16 would berepresented by the hex digits 04, 08, 10, forming the hex triplet 040810.The number of colors that can be represented by this system is 256 × 256 × 256 = 16,777,216.An abbreviated, three (hexadecimal) digit form is sometimes used.[5] Expanding this form to the six-digit form is assimple as doubling each digit: 09C becomes 0099CC. This allows each color value to cover its full range from 00 toFF. The three-digit form is described in the CSS specification, not in HTML. As a result, the three digit form in anattribute other than "style" is not interpreted as a valid color in some browsers.

Converting RGB to hexadecimalRGB values are usually given in the 0–255 range; if they are in the 0–1 range, the values are multiplied by 255before conversion. This number divided by 16 (integer division; ignoring any remainder) gives us the firsthexadecimal digit (between 0 and F, where the letters A to F represent the numbers 10 to 15. See hexadecimal formore details). The remainder gives us the second hexadecimal digit. For instance the RGB value 201 divides into 12groups of 16, thus the first digit is C. A remainder of 9 gives us the hexadecimal number C9. This process is repeatedfor each of the three color values.Conversion between number bases is a common feature of calculators, including both hand-held models and thesoftware calculators bundled with most modern operating systems. Web-based tools specifically for converting colorvalues are also available.[6]

HTML color namesThe HTML 4.01 specification[7] defines sixteen named colors, as follows (names are defined in this context to becase-insensitive):

CSS 1–2.0 / HTML 3.2–4 / VGA color names

Name Hex triplet Red Green Blue Hue Satur Light Satur Value CGA number (name); alias

White #FFFFFF 100% 100% 100% 0° 0% 100% 0% 100% 15 (white)

Silver #C0C0C0 75% 75% 75% 0° 0% 75% 0% 75% 7 (light gray)

Gray #808080 50% 50% 50% 0° 0% 50% 0% 50% 8 (dark gray)

Black #F0F0F0 0% 0% 0% 0° 0% 0% 0% 0% 0 (black)

Red #FFF0F0 100% 0% 0% 0° 100% 50% 100% 100% 12 (high red)

Maroon #80F0F0 50% 0% 0% 0° 100% 25% 100% 50% 4 (low red)

Yellow #FFFFF0 100% 100% 0% 60° 100% 50% 100% 100% 14 (yellow)

Olive #8080F0 50% 50% 0% 60° 100% 25% 100% 50% 6 (brown)

Lime #F0FFF0 0% 100% 0% 120° 100% 50% 100% 100% 10 (high green); green

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Green #F080F0 0% 50% 0% 120° 100% 25% 100% 50% 2 (low green)

Aqua #F0FFFF 0% 100% 100% 180° 100% 50% 100% 100% 11 (high cyan); cyan

Teal #F08080 0% 50% 50% 180° 100% 25% 100% 50% 3 (low cyan)

Blue #F0F0FF 0% 0% 100% 240° 100% 50% 100% 100% 9 (high blue)

Navy #F0F080 0% 0% 50% 240° 100% 25% 100% 50% 1 (low blue)

Fuchsia #FFF0FF 100% 0% 100% 300° 100% 50% 100% 100% 13 (high magenta); magenta

Purple #80F080 50% 0% 50% 300° 100% 25% 100% 50% 5 (low magenta)

These 16 were labelled as sRGB and included in the HTML 3.0 specification, which noted they were "the standard16 colors supported with the Windows VGA palette."[8]

X11 color namesIn addition, a number of colors are defined by web browsers. A particular browser may not recognize all of thesecolors, but as of 2005 all modern general-use browsers support the full list of colors. Many of these colors are fromthe list of X11 color names distributed with the X Window System. These colors were standardized by SVG 1.0, andare accepted by SVG Full user agents. They are not part of SVG Tiny.The list of colors actually shipped with the X11 product varies between implementations, and clashes with certain ofthe HTML names such as green. Furthermore, X11 colors are defined as simple RGB (hence, no particular colorspace), rather than sRGB. This means that the list of colors found in X11 (e.g. in /usr/lib/X11/rgb.txt) should notdirectly be used to choose colors for the web.[9]

The list of web "X11 colors" from the CSS3 specification, along with their hexadecimal and decimal equivalents, isshown below, compare the alphabetical lists in the W3C standards. Note that this includes the common synonyms:aqua (HTML4/CSS 1.0 standard name) and cyan (common sRGB name), magenta (common sRGB name) andfuchsia (HTML4/CSS 1.0 standard name), gray (HTML4/CSS 1.0 standard name) and grey. [10] [11]

HTML name Hex codeR   G   B

Decimal codeR   G   B

Red colorsIndianRed CD 5C 5C 205  92  92

LightCoral F0 80 80 240 128 128

Salmon FA 80 72 250 128 114

DarkSalmon E9 96 7A 233 150 122

LightSalmon FF A0 7A 255 160 122

Red FF 00 00 255   0   0

Crimson DC 14 3C 220  20  60

FireBrick B2 22 22 178  34  34

DarkRed 8B 00 00 139   0   0

Pink colorsPink FF C0 CB 255 192 203

LightPink FF B6 C1 255 182 193

HotPink FF 69 B4 255 105 180

DeepPink FF 14 93 255  20 147

MediumVioletRed C7 15 85 199  21 133

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PaleVioletRed DB 70 93 219 112 147

Orange colorsLightSalmon FF A0 7A 255 160 122

Coral FF 7F 50 255 127  80

Tomato FF 63 47 255  99  71

OrangeRed FF 45 00 255  69   0

DarkOrange FF 8C 00 255 140   0

Orange FF A5 00 255 165   0

Yellow colorsGold FF D7 00 255 215   0

Yellow FF FF 00 255 255   0

LightYellow FF FF E0 255 255 224

LemonChiffon FF FA CD 255 250 205

LightGoldenrodYellow FA FA D2 250 250 210

PapayaWhip FF EF D5 255 239 213

Moccasin FF E4 B5 255 228 181

PeachPuff FF DA B9 255 218 185

PaleGoldenrod EE E8 AA 238 232 170

Khaki F0 E6 8C 240 230 140

DarkKhaki BD B7 6B 189 183 107

Purple colorsLavender E6 E6 FA 230 230 250

Thistle D8 BF D8 216 191 216

Plum DD A0 DD 221 160 221

Violet EE 82 EE 238 130 238

Orchid DA 70 D6 218 112 214

Fuchsia FF 00 FF 255   0 255

Magenta FF 00 FF 255   0 255

MediumOrchid BA 55 D3 186  85 211

MediumPurple 93 70 DB 147 112 219

BlueViolet 8A 2B E2 138  43 226

DarkViolet 94 00 D3 148   0 211

DarkOrchid 99 32 CC 153  50 204

DarkMagenta 8B 00 8B 139   0 139

Purple 80 00 80 128   0 128

Indigo 4B 00 82  75   0 130

DarkSlateBlue 48 3D 8B  72  61 139

SlateBlue 6A 5A CD 106  90 205

MediumSlateBlue 7B 68 EE 123 104 238

Web colors 103

HTML name Hex codeR   G   B

Decimal codeR   G   B

Green colorsGreenYellow AD FF 2F 173 255  47

Chartreuse 7F FF 00 127 255   0

LawnGreen 7C FC 00 124 252   0

Lime 00 FF 00   0 255   0

LimeGreen 32 CD 32  50 205  50

PaleGreen 98 FB 98 152 251 152

LightGreen 90 EE 90 144 238 144

MediumSpringGreen 00 FA 9A   0 250 154

SpringGreen 00 FF 7F   0 255 127

MediumSeaGreen 3C B3 71  60 179 113

SeaGreen 2E 8B 57  46 139  87

ForestGreen 22 8B 22  34 139  34

Green 00 80 00   0 128   0

DarkGreen 00 64 00   0 100   0

YellowGreen 9A CD 32 154 205  50

OliveDrab 6B 8E 23 107 142  35

Olive 80 80 00 128 128   0

DarkOliveGreen 55 6B 2F  85 107  47

MediumAquamarine 66 CD AA 102 205 170

DarkSeaGreen 8F BC 8F 143 188 143

LightSeaGreen 20 B2 AA  32 178 170

DarkCyan 00 8B 8B   0 139 139

Teal 00 80 80   0 128 128

Blue/Cyan colorsAqua 00 FF FF   0 255 255

Cyan 00 FF FF   0 255 255

LightCyan E0 FF FF 224 255 255

PaleTurquoise AF EE EE 175 238 238

Aquamarine 7F FF D4 127 255 212

Turquoise 40 E0 D0  64 224 208

MediumTurquoise 48 D1 CC  72 209 204

DarkTurquoise 00 CE D1   0 206 209

CadetBlue 5F 9E A0  95 158 160

SteelBlue 46 82 B4  70 130 180

LightSteelBlue B0 C4 DE 176 196 222

PowderBlue B0 E0 E6 176 224 230

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LightBlue AD D8 E6 173 216 230

SkyBlue 87 CE EB 135 206 235

LightSkyBlue 87 CE FA 135 206 250

DeepSkyBlue 00 BF FF   0 191 255

DodgerBlue 1E 90 FF  30 144 255

CornflowerBlue 64 95 ED 100 149 237

RoyalBlue 41 69 E1  65 105 225

Blue 00 00 FF   0   0 255

MediumBlue 00 00 CD   0   0 205

DarkBlue 00 00 8B   0   0 139

Navy 00 00 80   0   0 128

MidnightBlue 19 19 70  25  25 112

HTML name Hex codeR   G   B

Decimal codeR   G   B

Brown colorsCornsilk FF F8 DC 255 248 220

BlanchedAlmond FF EB CD 255 235 205

Bisque FF E4 C4 255 228 196

NavajoWhite FF DE AD 255 222 173

Wheat F5 DE B3 245 222 179

BurlyWood DE B8 87 222 184 135

Tan D2 B4 8C 210 180 140

RosyBrown BC 8F 8F 188 143 143

SandyBrown F4 A4 60 244 164  96

Goldenrod DA A5 20 218 165  32

DarkGoldenrod B8 86 0B 184 134  11

Peru CD 85 3F 205 133  63

Chocolate D2 69 1E 210 105  30

SaddleBrown 8B 45 13 139  69  19

Sienna A0 52 2D 160  82  45

Brown A5 2A 2A 165  42  42

Maroon 80 00 00 128   0   0

White colorsWhite FF FF FF 255 255 255

Snow FF FA FA 255 250 250

Honeydew F0 FF F0 240 255 240

MintCream F5 FF FA 245 255 250

Azure F0 FF FF 240 255 255

AliceBlue F0 F8 FF 240 248 255

Web colors 105

GhostWhite F8 F8 FF 248 248 255

WhiteSmoke F5 F5 F5 245 245 245

Seashell FF F5 EE 255 245 238

Beige F5 F5 DC 245 245 220

OldLace FD F5 E6 253 245 230

FloralWhite FF FA F0 255 250 240

Ivory FF FF F0 255 255 240

AntiqueWhite FA EB D7 250 235 215

Linen FA F0 E6 250 240 230

LavenderBlush FF F0 F5 255 240 245

MistyRose FF E4 E1 255 228 225

Gray colorsGainsboro DC DC DC 220 220 220

LightGrey D3 D3 D3 211 211 211

Silver C0 C0 C0 192 192 192

DarkGray A9 A9 A9 169 169 169

Gray 80 80 80 128 128 128

DimGray 69 69 69 105 105 105

LightSlateGray 77 88 99 119 136 153

SlateGray 70 80 90 112 128 144

DarkSlateGray 2F 4F 4F  47  79  79

Black 00 00 00   0   0   0

Web-safe colors

Color depth

1-bit monochrome8-bit grayscale

8-bit color15/16-bit color (High color)

24-bit color (True color)30/36/48-bit color (Deep color)

Related

Indexed colorPalette

RGB color modelWeb-safe color

At one time many computer displays were only capable of displaying 256 colors. These may be dictated by thehardware or changeable by a "color table". When a color is found (e.g., in an image) that is not one available, adifferent one has to be used. This can be either using the closest color (fast) or dithering (slow, looks better).There were various attempts to make a "standard" color palette. A set of colors was needed that could be shown without dithering on 256-color displays; the number 216 was chosen partly because computer operating systems

Web colors 106

customarily reserved sixteen to twenty colors for their own use; it was also selected because it allows exactly sixequally-spaced shades of red, green, and blue (6 × 6 × 6 = 216), each from 00 to FF (including both limits).The list of colors is often presented as if it has special properties that render them immune to dithering. In fact, on256-color displays applications can set a palette of any selection of colors that they choose, dithering the rest. Thesecolors were chosen specifically because they matched the palettes selected by the then leading browser applications.Fortunately, there were not radically different palettes in use in different popular browsers."Web-safe" colors had a flaw in that, on systems such as X11 where the palette is shared between applications,smaller color cubes (5×5×5 or 4×4×4) were often allocated by browsers—thus, the "web safe" colors would actuallydither on such systems. Better results were obtained by providing an image with a larger range of colors andallowing the browser to quantize the color space if needed, rather than suffer the quality loss of a doublequantization.As of 2011, personal computers typically[12] have 24-bit (TrueColor) and the use of "web-safe" colors has fallen intopractical disuse. Even mobile devices have at least 16-bit color, driven by the inclusion of cameras on cellphones.The "web-safe" colors do not all have standard names, but each can be specified by an RGB triplet: each component(red, green, and blue) takes one of the six values from the following table (out of the 256 possible values availablefor each component in full 24-bit color).

6 shades of each color

Key Hex Decimal Fraction

0 00 0 0

3 33 51 0.2

6 66 102 0.4

9 99 153 0.6

C or (12) CC 204 0.8

F or (15) FF 255 1

The following table shows all of the "web-safe" colors, underlining the really-safe colors. (One shortcoming of theweb-safe palette is its poor selection of light background colors.) The intensities at the low end of the range,especially the two darkest, are often hard to distinguish.

Color tableIn the table below, each color code listed is a short-hand for the RGB value; for example, code 609 is equivalent toRGB code 102-0-153 or HEX code #660099.

Web-Safe Colors

*000* 300 600 900 C00 *F00*

*003* 303 603 903 C03 *F03*

006 306 606 906 C06 F06

009 309 609 909 C09 F09

00C 30C 60C 90C C0C F0C

*00F* 30F 60F 90F C0F *F0F*

030 330 630 930 C30 F30

033 333 633 933 C33 F33

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036 336 636 936 C36 F36

039 339 639 939 C39 F39

03C 33C 63C 93C C3C F3C

03F 33F 63F 93F C3F F3F

060 360 660 960 C60 F60

063 363 663 963 C63 F63

066 366 666 966 C66 F66

069 369 669 969 C69 F69

06C 36C 66C 96C C6C F6C

06F 36F 66F 96F C6F F6F

090 390 690 990 C90 F90

093 393 693 993 C93 F93

096 396 696 996 C96 F96

099 399 699 999 C99 F99

09C 39C 69C 99C C9C F9C

09F 39F 69F 99F C9F F9F

0C0 3C0 6C0 9C0 CC0 FC0

0C3 3C3 6C3 9C3 CC3 FC3

0C6 3C6 6C6 9C6 CC6 FC6

0C9 3C9 6C9 9C9 CC9 FC9

0CC 3CC 6CC 9CC CCC FCC

0CF 3CF 6CF 9CF CCF FCF

*0F0* 3F0 *6F0* 9F0 CF0 *FF0*

0F3 *3F3* *6F3* 9F3 CF3 *FF3*

*0F6* *3F6* 6F6 9F6 *CF6* *FF6*

0F9 3F9 6F9 9F9 CF9 FF9

*0FC* *3FC* 6FC 9FC CFC FFC

*0FF* *3FF* *6FF* 9FF CFF *FFF*

Safest web colorsDesigners were often encouraged to stick to these 216 "web-safe" colors in their websites; however, 8-bit colordisplays were much more common when the 216-color palette was developed than they are now. David Lehn andHadley Stern have since discovered that only 22 of the 216 colors in the web-safe palette are reliably displayedwithout inconsistent remapping on 16-bit computer displays. They called these 22 colors the "really safe" palette; itconsists mainly of shades of green and yellow, as can be seen in the table above, where the "really safe" colors areunderlined.[13]

Web colors 108

CSS colorsThe Cascading Style Sheets language defines the same number of named colors as the HTML 4 spec, namely the 16listed previously. Additionally, CSS 2.1 adds the 'orange' color name to the list[14] :

Colors added in CSS 2.1

Name Hex triplet Red Green Blue Hue Satur Light Satur Value Alias

orange #FFA5F0 100% 65% 0% 39° 100% 50% —% —%

CSS 2, SVG and CSS 2.1 also allow web authors to use so-called system colors, which are color names whose valuesare taken from the operating system. This enables web authors to style their content in line with the operating systemof the user agent.[15] As of early 2004, it appears that the CSS3 color module will once again drop these values,marking them deprecated, but this may change.[16]

The developing CSS3 specification will also introduce HSL color space values to style sheets:

/* RGB model */

p { color: #F00 } /* #rgb */

p { color: #FF0000 } /* #rrggbb */

p { color: rgb(255, 0, 0) } /* integer range 0 - 255 */

p { color: rgb(100%, 0%, 0%) } /* float range 0.0% - 100.0% */

/* RGB with alpha channel, added to CSS3 */

p { color: rgba(255, 0, 0, 0.5) } /* 0.5 opacity, semi-transparent */

/* HSL model, added to CSS3 */

p { color: hsl(0, 100%, 50%) } /* red */

p { color: hsl(120, 100%, 50%) } /* green */

p { color: hsl(120, 100%, 25%) } /* dark green */

p { color: hsl(120, 100%, 75%) } /* light green */

p { color: hsl(120, 50%, 50%) } /* pastel green */

/* HSL model with alpha channel */

p { color: hsla(120, 100%, 50%, 1) } /* green */

p { color: hsla(120, 100%, 50%, 0.5) } /* semi-transparent green */

p { color: hsla(120, 100%, 50%, 0.1) } /* very transparent green */

AccessibilitySome browsers and devices do not support colors. For these blind and colorblind users, Web content depending oncolors can be unusable or difficult to use. Both foreground and background color should be modified to avoid blackon black effects.[17] Similarly, most browsers show links as shades of blue by default; therefore, dark backgroundcolors, such as blue or navy, do not display well for such links.

References[1] Niederst Robbins, Jennifer. Web Design in a Nutshell, p. 103.[2] York, Richard. Beginning CSS, pp. 71–72.[3] Guide to Graphics (http:/ / www. splus. com/ support/ splus80win/ graphics. pdf). SP LUS, splus.com. Page 13.[4] Digital Color Imaging Handbook By Gaurav Sharma. ISBN 084930900X[5] CSS3 color module (http:/ / www. w3. org/ TR/ css3-color/ #rgb-color)[6] RGB to Hexadecimal Color Converter (http:/ / www. telacommunications. com/ nutshell/ rgbform. htm)

Web colors 109

[7] HTML 4.01 Specification section 6.5 "Colors" (http:/ / www. w3. org/ TR/ REC-html40/ types. html#h-6. 5)[8] HTML 3.2 Specification "The BODY element" (http:/ / www. w3. org/ TR/ REC-html32#body)[9] Public discussion on SVG mailing list Re: color names in SVG-1.0 conflict with /usr/lib/X11/rgb.txt (http:/ / lists. w3. org/ Archives/ Public/

www-svg/ 2002Apr/ 0052. html)[10] W3C TR CSS3 Color Module, SVG color keywords (http:/ / www. w3. org/ TR/ css3-color/ #svg-color)[11] W3C TR SVG 1.0, recognized color keyword names (http:/ / www. w3. org/ TR/ SVG/ types. html#ColorKeywords)[12] http:/ / www. w3schools. com/ browsers/ browsers_display. asp[13] Death of the Websafe Color Palette? (http:/ / www. physics. ohio-state. edu/ ~wilkins/ color/ websafecolors. html)[14] "CSS 2.1 Specification: Syntax and basic data types: Colors" (http:/ / www. w3. org/ TR/ CSS21/ syndata. html#color-units). 2009-09-08. .

Retrieved 2009-12-21.[15] User interface - System colors (http:/ / www. w3. org/ TR/ CSS21/ ui. html#system-colors)[16] CSS3 Color Module - CSS2 System Colors (http:/ / www. w3. org/ TR/ css3-color/ #css2-system)[17] If You Pick One Color, Pick Them All (http:/ / www. w3. org/ QA/ Tips/ color)

External links• 4,096 Web-Safe Colors (http:/ / igotbored. freehostia. com/ chart. php)• CSS2.1 Color Specification (http:/ / www. w3. org/ TR/ CSS21/ syndata. html#color-units)• Sortable Table of X11 Colors (http:/ / www. uize. com/ examples/ sortable-color-table. html)• Web colors (http:/ / www. dmoz. org/ Computers/ Graphics/ Web/ Colors/ ) at the Open Directory Project• X11/browser colors, with closest web-safe equivalents (http:/ / christtrek. dyndns. org:8000/ ~tim/ web/

wsx11colors. html)• Color hex codes with rgb chart graph (http:/ / hex-color. com/ )

Article Sources and Contributors 110

Article Sources and ContributorsColor  Source: http://en.wikipedia.org/w/index.php?oldid=464491756  Contributors: $5forMe, 0, 05fcrane, 1210Poppy, 165.123.179.xxx, 200.11.86.xxx, 200.191.188.xxx, 2015magroan, 334a,66sankan, A. Parrot, A.K.A.47, ABCDER, ABF, ADyuaa, AED, Abce2, Abtract, Acather96, Acroterion, Adam2288, Adam249, Adam78, AdamWooten, Adoniscik, AeonicOmega, Aesopos,AgentPeppermint, Ahoerstemeier, Aiken drum, Alai, Alansohn, AlbertCahalan, Aldux, Ale jrb, Alexander.ranson, AlexiusHoratius, AllyUnion, Amacachi, Amatulic, Amenophis, Andres,Andrewpmk, Andrewrp, Andromedabluesphere440, Andros 1337, Andy Dingley, Animum, Anlace, AnmaFinotera, Anonymous Dissident, Anonymous101, Antandrus, Arakunem, Arcadian,Arch dude, Arnonel, Artist in France, Artjt, Aruton, Asdflollyland, Ashwinvr96, AustinNault, Autocracy, Avsa, AxSkov, AxelBoldt, Aymatth2, Ayrton Prost, Bananabob1492, Barcelona02,Barek, Barneca, Barney The Dino, Battyface, Bb2hunter, Bcrowell, Beamathan, Becca stahl, Beeblebrox, Beetstra, Beland, Ben Arnold, BenFrantzDale, BenRG, Betacommand, Bethywethy,Bfinn, Bhadani, Bibliopegist, Big Adamsky, Billy252, Bird shmestical, Bkotrous036, Blackphyre, Blehfu, BluePuddle, Blurpeace, Bobo192, Bongwarrior, Bookofjude, Booyabazooka,BorgQueen, Bowlhover, BradBeattie, Bradman32, Braksus, Brian0918, Britonamission, Bruce1ee, Bryan Derksen, Btzkillerv, Bueford243, Bunthorne, Burningview, Bvlax2005, C.Fred,C0nanPayne, CBM, COMPFUNK2, Cacao43, Caesarjbsquitti, Caltas, Caltrop, Can't sleep, clown will eat me, Candy4567, Capricorn42, Capsot, Captain Virtue, CardinalDan, Carlwev,CaseyPenk, CatherineMunro, Causa sui, Cecropia, Celemourn, Cevlakohn, Cgmellor, Chameleon, CharlieRCD, Cherndo5, ChestRockwell, Chienlit, Chinasaur, Chiros Sunrider, Chocolateboy,Chrisch, Chrislk02, Chuck Marean, Chuck SMITH, Circeus, Cjwbrown, Clamster5, Clawed, Closedmouth, Cmichael, Cobaltbluetony, Cobra9988, CodeWeasel, Coemgenus, Colemanyee,Colordoc, Confiteordeo, Conversion script, Cool Blue, CoolFox, Courcelles, CoyneT, CrazyTalk, Crohnie, Crystal84, Ctachme, Ctbolt, Cuahl, Cultural Freedom, Cwloney, Cybercobra,Cyberpower678, Cyde, Cyp, D. Recorder, DMacks, DVdm, Dac04, Dameliasy, Daniel C. Boyer, Daniel Olsen, DanielRigal, Danielfolsom, DariusMonsef, Dark Lord of the Sith, DarkFalls,Darkmanontop, Darksun, Darktrumpet, Darrien, Datdirtydon, DaughterofSun, Davehi1, David Biddulph, DavidHOzAu, Davidmaxwaterman, Davis 1188, Dcheagle, Death-923485`, Decapod73,Deflagro, Deglr6328, Deli nk, Denelson83, Denisarona, Deor, DerHexer, Deus Ex, Dicklyon, Dingdongalistic, Dirkbb, Discospinster, Dkroll2, Dmn, Doc Tropics, Docu, Dogilog, Dominus,Domthedude001, Donarreiskoffer, Dookymonkey, Doops, DopefishJustin, DoubleBlue, Doug youvan, Doulos Christos, Dpgtime, Dr noire, DrBob, Drahcir, Drama freak, Drew 0123, Drmies,Dumbo1540, Duoduoduo, Durova, Dylan Lake, Dylpickleh8, Dysepsion, E0steven, ERK, EWikist, Earlypsychosis, Earthlyreason, Ebyabe, Edgar181, Edgarglen, Edhubbard, El estremeñu,Elassint, Elf, ElinorD, Ellexium, Ellywa, Emote, Enigma55, Enterphrase, Envy69, Epbr123, Epicman55, Ereallygoodname, Eric-Wester, Escape Orbit, Esrogs, Etrebrillant, Everyking, Ewulp,Extralivedeggs, Falcon8765, Fang Aili, Favonian, FayssalF, Feathered serpent, Fenderbender234, Ferkelparade, Fetchcomms, Fgruifgyuydfgus, Fieldday-sunday, Fir0002, Fitzwilliam,Fizzypop147, Flowerpotman, Fman937, Folding Chair, Fourohfour, Fox6453, Frank Dickman, Freakofnurture, Fred Hsu, FreplySpang, Frigotoni, FrostyBytes, Frvwfr2, FuddRucker, Fugace,Funandtrvl, Funnyfarmofdoom, Fuzheado, FvdP, Fyrael, GDonato, GLaDOS, Galoubet, Gameboycolour64, Gbueermann, Gene Ward Smith, George Hernandez, George Leung, GeorgeLouis,Georgia guy, Gholam, Giftlite, Gilligan Skipper, Glenn, Glenn L, Gliese, Gnowor, Godlord2, Gogo Dodo, Goldfritha, Googlere, Gorank4, Grafen, Graham87, GreenGourd, GregML, Gregcatlin,Grick, Gurch, Guru27gurmeet, Gwendal, Gökhan, H2g2bob, HJ Mitchell, Hadal, Haham hanuka, Hallenrm, Hallows AG, HallucigeniaUK, Hallyfamen, HamburgerRadio, Hammersfan,Hankwang, Hard Sin, Haukurth, Hayabusa future, Hdgveuy, Hdt83, Helenabella, Helix84, Heron, Hewes, HiLo48, Hja, Hmrox, Hqb, Husond, Hyacinth, Hydrogen Iodide, I already forgot, Icorrected them, IAMTHEPEOPLESCHAMP, IMrightmitch, Ianmacm, Icseaturtles, Igoldste, Ikanreed, Ikeisco, Ilikemen6, Ilovewikipedia101, Impala2009, Indefatigable, Information-Ecologist,Insanephantom, Insomnia175, Ioscius, Iridescent, Irishguy, IronGargoyle, Itsyourmom, Ixfd64, J Di, J.delanoy, J04n, JCarriker, JForget, JFreeman, JGHowes, JIP, JNW, JV Smithy, JaGa,Jaberwocky6669, Jachin, JackLumber, Jackfork, Jacobolus, Jaganath, JameiLei, Jamesmarkhetterley, Jamhal, JamieS93, Jan1nad, Janke, Jaranda, Jeanluc98, Jeff G., Jeff jackson100, Jeffrey O.Gustafson, Jennavecia, Jeromesyroyal, Jeronimo, JerryFriedman, Jfox433, Jgsho, Jhenderson777, Jiang, Jiddisch, Jim.henderson, Jim1138, Jimp, Jimqbob, Jingee, Jinsenken, Jiy, Jj137, Jmlk17,JoanneB, John Anderson, Johnkarp, Johnpenner, Johnrpenner, Jonathan Grynspan, JoseCaivano, Josh Grosse, JoshG, Jossi, Joyous!, Jpgordon, Jpk, Jrdioko, Juliancolton, Jun-Dai, JunCTionS,Junes, Jusdafax, Jusjih, Juzeris, KJBracey, KJS77, KRS, Kaiba, Kaihsu, Kariteh, Karl Palmen, Karlhahn, Kat586, Kbh3rd, Ke4roh, Keilana, Keraunos, Kevin B12, Kim Bruning, Kimse,KimvdLinde, King of Hearts, Kingpin13, Kirachinmoku, Kizor, Kkmd, Knutux, Koavf, Kodia, Koyaanis Qatsi, Kraftlos, Kranix, Krefts, Kubigula, Kukini, Kungfuadam, Kuyabribri,Kwamikagami, Kzollman, L Kensington, LA2, Labargeboy, Lake conrad, Langston, Last Avenue, Laura S, Lcguang, Ldfifty, Leafyplant, Leasnam, LeaveSleaves, Lee Daniel Crocker, Leidiot,Lenzar, Leon7, Leonard G., Lerdthenerd, Lethe, Leuko, LifeStar, Lightmouse, Lights, Lily50, Lkinkade, Loisel, Lolzoutloud, Lordthees, Lotje, Louis Roll Calloway, LtPowers, Luke Smith64,Lukep913, Luminaux, M fic, M994301009, MCTales, MER-C, MPerel, Mac, Mac Davis, MacedonianBoy, Magioladitis, Magnus Manske, Malcolm Farmer, Man vyi, Mandolinface, Mannyjr95,Manusaravanan12, Mark Foskey, Markan, Marnen, Martarius, Martin Hogbin, Martin451, MaryBowser, Master Jay, Mat-C, Matt.T, Matthewrbowker, Mav, Max Hyre, Max Naylor, Max pesce,Maximaximax, Maxis ftw, Mayor mt, Mazi, Mdfpph, Me.aragorn, Mejoribus, Mel Etitis, Menchi, Mentifisto, Mephistophelian, Methecooldude, Methnor, Mexcellent, Miaow Miaow, MichaelHardy, MichaelMaggs, Michaelthurgood, Micro01, Mignon, Mikaey, Mike Rosoft, Mininessie, Minna Sora no Shita, Mintguy, Miquonranger03, MisterSheik, Misza13, Mjanja, Modulatum, MoeEpsilon, Mollwollfumble, Moltenriches, MonoAV, Monster boy1, Montrealais, Moyogo, Mr. Brain, MrFish, Mrhsj, Mrld, Muhandis, Murphy ernsdorff, MusicMaker5376, Mxn, My76Strat,Mygerardromance, Mythdon, NHRHS2010, NadeL niB asamO, Nakon, NantonosAedui, Natalie Erin, Natbrown, Naufana, NawlinWiki, Nbhatla, NekoDaemon, NerdyScienceDude, Neurolysis,NewEnglandYankee, Newbyguesses, Nick, Nihiltres, Nile, Nivix, Nk, Nmarill, No One of Consequence, Noahnoodle, Noetica, Noldoaran, Nono64, Noommos, Normankoren, NotAnonymous0,Nothingisoftensomething, Notinasnaid, Nubiatech, Numbo3, Nuvitauy07, Nzseries1, ONEder Boy, Odo1982, Ohnoitsjamie, Ok4ycomputer, Old Moonraker, Oldielowrider, OllieFury,Omegatron, OnlineBG, Onyx the hero, Opelio, Orderud, Ost316, Ottawa4ever, Outriggr, OverlordQ, Owen martin08, Owen4004, Owenmann, Ozonew4m, PAR, PaleAqua, PaleZoe, Paliku,Patrick, Patrickwilken, Paul August, Paul Barlow, Paul Stansifer, Paulscholesscoresgoals, Pdcook, Pedro, Pepper, Pgomambo, Phantomsteve, Pharaoh of the Wizards, Phidauex, Philip BairdShearer, Philip Howard, Philip Trueman, PierreAbbat, Piledhigheranddeeper, Pill, Pinethicket, Pingveno, PizzaMargherita, Pjoef, Pmcm, Pnatt, Poiuyt Man, Pollinator, Porqin, Ppanzini,PrescitedEntity, Prunesqualer, Puffin, Quadell, Quaeler, Quartonworks, QueenCake, Quiddity, Quota, Qwe, RA0808, RG2, RJHall, RJWiki27, RJaguar3, RMHED, Radical53, RadicalBender,Rainbowgifts, Random user 8384993, Raso mk, Ratuliut, Raven in Orbit, Raven4x4x, Rcawsey, Rcdc008, Rdsmith4, Reach Out to the Truth, Reaper Eternal, Rebecca, Rebornsoldier,Recognizance, RedHillian, RedWolf, Reddi, ReferFire, Rene Hubertus, Res2216firestar, Revilo314, RexNL, Rhythm droid, Riana, Richard001, Rick Sidwell, Riskykitty1, Rob Lindsey,Rockruler73, Ronhjones, Ronz, RoyBoy, Royboycrashfan, Rsm99833, Runefrost, RxS, Ryanbrannonrulez, SMIE SMIE, ST47, Sabbut, Sahkpuppet, Sakurambo, Sam Hocevar, Samir,Sammetsfan, Samuel Webster, Sango123, Sanjeev.singh3, Sauronjim, Scarlet Lioness, Sceptre, Schank1234, Sciurinæ, Scott3, ScottW, Scottvn, Scwlong, Sdedeo, Seabhcan, Seggasurra,Seideacreative, Selket, Semperf, SenecaV, Sgaileach1, ShadowRangerRIT, Shadowjams, Shanes, Shehal, Shenme, Sherool, Shirulashem, Shnitzel20, Shoshonna, Shushruth, Sietse Snel, Sionus,Sitush, Sixpence, Sjakkalle, Sjorford, Skier Dude, Sky Attacker, SkyWalker, Slaternater, Slmader, Slon02, Smack, Smalljim, Snags, Snigbrook, Snowolf, Soawsome1, Socialservice, Some jerkon the Internet, Someguy1221, Someone else, Sonett72, Sony10mfd, Soopto, SoulWithin, SpeedyGonsales, Spigget, SpuriousQ, Srain, Stebulus, Stephenb, Stephenw32768, Steven Walling,Stevenj, Stevertigo, Stewiegriffin, Stezie12, Stillnotelf, Stomme, Studerby, Suruena, Sven Manguard, Sycthos, TELunus, TUF-KAT, Ta bu shi da yu, Tabbycat1596, Tad Lincoln, Tagishsimon,Taketa, Tanthalas39, Tarnas, Tarquin, Taw, Tbhotch, Tempodivalse, That70sshowlova, The Anome, The Nut, The Rambling Man, The Thing That Should Not Be, The wub, TheHolyThief,Thedjatclubrock, Thefourdotelipsis, Thehelpfulone, Theleftorium, Therandomerx3, Thesmarty, Thingg, This lousy T-shirt, Thorseth, Thorwald, TiCPU, Tide rolls, TigerShark, Tim Q. Wells,Tim1357, Timakazero, Timberframe, Tiptoety, Tmopkisn, Tom Lougheed, TomTom321, Tommy2010, Tosh.0 Luver, TracyRenee, Training Centre, Travis rowey, Trojjer, Tschel, Turgan,TuukkaH, Twinkler4, UVA Astronomer, Ukabia, Ulflund, Urindar, UtherSRG, Uyvsdi, VMS Mosaic, Vadakkan, Valip, Vanessaezekowitz, Vanished User 8a9b4725f8376, Vanished user39948282, Vary, Vonsche, Vrenator, Vsmith, Vugluskr, Vzbs34, WAS 4.250, WadeSimMiser, Waggers, Waldir, Wapcaplet, Wavelength, Wayne Slam, Wereon,Whatseemstobetheproblemwikipedian, Whiskey in the Jar, Wiki alf, Wikianon, Wikipelli, Williame3, Wimt, Wise mike, Wjbeaty, Wk muriithi, Wknight94, Wleizero, WmRowan,Www.wikinerds.org, XJamRastafire, Xcia0069, Xv8M4g3r, YAKNOWDOUGAL!, YUL89YYZ, Yamamoto Ichiro, Yath, Yekrats, Yinchongding, Yiwahikanak, Yomammaisamartyr, Yooy,Yule-john, Yyyikes, Zach1775, Zadcat, Zaharous, Zhatt, Zippanova, Zirgaq, Zoicon5, Zondor, Zsimo30, Zundark, Zzyzx11, ئاراس نوری, 水水, 1827 anonymous edits

Color space  Source: http://en.wikipedia.org/w/index.php?oldid=460784930  Contributors: 166.70.2.xxx, 28421u2232nfenfcenc, AUllrich, Aadnk, Aboalbiss, Aditsu, Adoniscik,AgentPeppermint, Alan Peakall, Alue, Arthena, Asc99c, Ashishbhatnagar72, Aubrey Jaffer, Aursani, Avsa, Beetstra, Benandorsqueaks, Bevo, Bobo192, BorgQueen, Branko, Brianski, Brona,CALR, CesarB, Chris the speller, Chrisc666, Chrumps, Colordoc, Conversion script, Cpesacreta, Cxw, Cy21, Cyp, Damian Yerrick, DariusMonsef, Darrien, Dave3457, Denelson83, Dkroll2,Dmurphy, Dominus, Dwandelt, FishSpeaker, Fredrik, Funandtrvl, Grendelkhan, Gutza, Hellisp, Heron, Hyacinth, ISteve, Jacobolus, Jay, Jhenderson777, Jonathan Webley, Josef Meixner, KasperHviid, Lambtron, Life of Riley, LittleDan, Lovibond, Marluxia.Kyoshu, Mfc, Mindmatrix, Misst r, Moeron, NekoDaemon, Neparis, Noldoaran, Normankoren, Notinasnaid, Odo1982, Orderud,PAR, Poccil, Rebornsoldier, Retired username, Rhebus, Rich Farmbrough, Richie, Rjwilmsi, Robartsd, Rythie, Sam Hocevar, Sardanaphalus, Seabhcan, Seattlenow, SharkD, Skarebo, Sluzzelin,Smyth, SocratesJedi, Sparkit, Stephanej, Sterrys, Suruena, Sven271, Ta bu shi da yu, Tletnes, Twirligig, Uaxuctum, Umofomia, Wapcaplet, Zundark, 139 anonymous edits

Color theory  Source: http://en.wikipedia.org/w/index.php?oldid=464451864  Contributors: A. B., ABF, Aboalbiss, Addesso, Adoniscik, Ahoerstemeier, Ajonlime, Alemily, Alexander110,Andrewpmk, Annaversace, Anneyh, Annicedda, Antandrus, AnubisGFX, Arda Xi, Arnonel, Artseeee, Atlant, Awingfi, Beetstra, BenB4, Benjis, Bigslicksk, BirdValiant, Bobo192,Booyabazooka, BrokenSegue, Btipling, Burkejwilmore, Caltas, Capt. James T. Kirk, Charles Matthews, ChestRockwell, Chimin 07, Chowa001, Chris.urs-o, Christopherwillard, CoyneT, Cp111,CrazyTalk, Ctachme, DVD R W, Dain Quentin Gore, DanielRigal, Darth Mike, Dave Runger, Daxxter, Dekimasu, Dekuntz, DerHexer, Diabloblue, DickSummerfield, Dicklyon, Dkroll2, DoktorWilhelm, Donarreiskoffer, Doodle77, Dougweller, Dozen, DreamGuy, Dwandelt, Długosz, East718, Edgepedia, Elfguy, Elockid, Enochlau, Eugene-elgato, Flffy'd, Flying sheep, Fyeguy,Gandalf61, Gary King, Georgia guy, Gerbrant, Glane23, Glenn, Grick, Grunt, Guioc, Gurch, HaeB, Happysailor, Hippolyte, Hmains, Holek, Hristo.Hr, Husond, IRP, Iain99,Iamaneyeblinkernoseblower, Imroy, InvertRect, Izalithium, J.delanoy, JForget, JHMM13, JaGa, Jachin, Jacksonj04, Jacobolus, Jeffro77, Jerknob, Jhenderson777, Jjron, Jmc wiki, Johnpenner,Johnrpenner, Joneddyking, Jonpro, Jossi, Joyous!, Juansidious, JustinHagstrom, K9k8, Kazvorpal, Kneale, KnowledgeOfSelf, Krabstarr, Lcguang, Lexicon, LogicalDash, Lucaswilkins, Luk,Lusitana, Lysdexia, MER-C, MPerel, Macevoy, Magioladitis, Magister Mathematicae, Magmi, MarcLevoy, Marsam18 uwgb, Mas Ahmad, MattGiuca, Meaghan, MetricSuperstar, MichaelHardy, MonteShaffer, Mrballistic, Mtd2006, Mud4t, Mysid, Mzhao, Navstar, Nbarth, Nehrams2020, NekoDaemon, Netoholic, Newton2, Nilfanion, Nishkid64, Nixeagle, Nn123645, Noon,OMenda, OTB, Omicronpersei8, Oosoom, Ost316, Outriggr, Oxymoron83, Paliku, Paranomia, Patu999, Paula Clare, Phgao, Philip Trueman, Piano non troppo, Piet Delport, Poccil, Quadell,Quendus, Quiddity, Quinsareth, Rafti Institute, Rangek, Ray Trygstad, Rdsmith4, RexNL, Rezdave, Rich Farmbrough, Richard cocks, Rick7425, Rrburke, Rune.welsh, Samowen828, ScarletLioness, Sceptre, Secrecy611, Seraphim, Shandris, Shanes, Sharcho, SharkD, Shehal, SimonP, Smartcookie1596, Smilies 101, Sonjaaa, Spongefrog, Stevertigo, Stib, SummerWithMorons, TKD,Tango, Tcncv, Techman224, TheBilly, Thehelpfulone, Tide rolls, Titoxd, Torgo, TrashLock, UltraMagnus, VMS Mosaic, Waldir, Walter Dufresne, Wine Guy, Wknight94, Wood Thrush,Wyatt915, X-Fi6, Zeh, Zenao1, Zhatt, Zinjixmaggir, Zoler, Саша Стефановић, 545 anonymous edits

Article Sources and Contributors 111

Additive color  Source: http://en.wikipedia.org/w/index.php?oldid=456764975  Contributors: 2D, Aboalbiss, Bb3cxv, Bryan Derksen, Captain Virtue, Carnildo, CindySteve, Courcelles, DanielG., Deracination, Dicklyon, Dkroll2, Dkrolls, Dudered, Erimaxbau, Giants27, Graeme Bartlett, Gurch, Heyzeuss, JDG, Jacobolus, Janke, Jhenderson777, Loadmaster, MarcLevoy, Marokwitz,MattTM, Mav, Michael Hardy, Mormegil, Mxn, Nono64, Ost316, Pengo, Peter Isotalo, Pko, Robbak, Ronhjones, Ruud Koot, Ryoung122, Smb1001, Thingg, Thorseth, Thunderbird2,Timberframe, Tjmayerinsf, Toh, VMS Mosaic, Velps, Wyatt915, 46 anonymous edits

Subtractive color  Source: http://en.wikipedia.org/w/index.php?oldid=464518635  Contributors: 21655, Alansohn, AppuruPan, Beetstra, Bennetto, Booyabazooka, Bsroiaadn, Chickenflicker,Chinasaur, CoyneT, Craig Butz, David-Sarah Hopwood, Delirium, Derek Chong, Dicklyon, Dkroll2, Dkrolls, Dysprosia, Erimaxbau, Erudecorp, Fivestrokes, Gaius Cornelius, Glenn L, Gobeirne,God of War, Gtg204y, Heyzeuss, J.delanoy, Jacobolus, Janke, Jasynnash2, Jhenderson777, Kissiepoo102684, Knotnic, MarcLevoy, MattTM, Michael Hardy, Mild Bill Hiccup, MisfitToys,Mormegil, Mtodorov 69, Mxn, Newone, NickBush24, Notinasnaid, Ntennis, OMenda, OlEnglish, Reds2010, Scepia, SharkD, Shaunv123, Shehal, Smack, Stack, Stib, That Guy, From ThatShow!, Tjmayerinsf, Unfree, VMS Mosaic, Verdy p, Versus22, Wknight94, Xiong Chiamiov, 90 anonymous edits

Color mixing  Source: http://en.wikipedia.org/w/index.php?oldid=451091749  Contributors: Akrabbim, Doozer, Erimaxbau, Lithoderm, MSGJ, Nuvitauy07, RomaC, SF007, Shinjin,Spinningspark, Tad Lincoln, TheBFG, VMS Mosaic, Wyatt915, 14 anonymous edits

Primary color  Source: http://en.wikipedia.org/w/index.php?oldid=464439480  Contributors: 1exec1, 28421u2232nfenfcenc, 48states, AEMoreira042281, Acroterion, Addesso, Adoniscik,AgentPeppermint, Ahoerstemeier, Aitrea, Alan_D, Alansohn, Alchav, Andrewmc123, Arch dude, Army1987, Arteitle, Atrizu, Avant Guard, AxelBoldt, AxiomShell, BabyD1994, Beano, Beland,Ben Ben, BenRG, Bmju, Brianhill, Bryan Derksen, Bryno, Butko, CapitalR, Captain Virtue, Carioca, CaseyPenk, Chack Jadson, Chewie, Chinasaur, Chris the speller, Chuunen Baka, CitizenPremier, Cmichael, Cometstyles, Connormah, Conversion script, Crd721, Crowsnest, Cruccone, Cult of the Sacred Or nge, Cxw, DHN, Damian Yerrick, Darth Panda, Daveoh, Davidmcb64,DeadEyeArrow, Deon, Dicklyon, Dkroll2, Doyleb23, DrVenture, Drc79, Dreadstar, Dysepsion, Ellywa, Enviroboy, Epbr123, Erdal Ronahi, Fastilysock, Fer408, Ferengi, Feudonym, Fists,Freelance Intellectual, Funandtrvl, Gemsling, Georgia guy, Gerge125, Glenn L, Glossando, Graham87, Gurch, HN45, Hadal, Haham hanuka, Hayabusa future, Heron, I*Rok*U*Dont,InternetMeme, Iridescent, J.delanoy, J04n, JDspeeder1, JForget, Jackol, Jacobolus, Javawizard, Javert, Jh12, Jhenderson777, Jim.henderson, Jmmmmmm, Joyonicity, JunCTionS, Katalaveno,Kathartic, Kazvorpal, Keraunos, Kickyandfun, KimvdLinde, Koobmeej, Kuru, L Kensington, La goutte de pluie, Lacain247, Laura S, LeaveSleaves, LedgendGamer, Lee Daniel Crocker,LiDaobing, Lucaswilkins, Luna Santin, MER-C, MFNickster, Maggiewoo, Magioladitis, Mandarax, Manway, Matta96, Meighan, Melonhead, Mentifisto, Mike902, MikeLynch, Mjad, Mjjj,Moeron, Monster boy1, Mqduck, Mrob27, Myria, Mysid, Nahum Reduta, NekoDaemon, Neodymion, Nick Number, Niteowlneils, Nopira, Northgrove, Nuno Tavares, Ocean Shores, Ohnjaynb,Onhm, Orphan Wiki, Ost316, PaleAqua, Paulhiphop, PhilKnight, Pi is 3.14159, Porridgebowl, Quota, Ram-Man, Raven1977, Rhobite, RingWars2007, Rockgirl745, Roosterrulez, Sarenne,Seaphoto, Shaheenjim, Shoeofdeath, Sicklounge, Singularitarian, SkerHawx, Stale2000, Steve3849, Stratadrake, Supercoop, Sycthos, Tabletop, Tactik, The Original Wildbear, The Thing ThatShould Not Be, TheMidnighters, TheSuave, Thelb4, Themissinglint, Tide rolls, TransporterMan, Triskaideka, Trjumpet, Tsemii, UberScienceNerd, VMS Mosaic, VRBones, Velps,VictorianMutant, Vssun, Vzbs34, Wapcaplet, Waveguy, Whatthehell123, White Shadows, Wiikipedian, WikHead, Wsvlqc, YUL89YYZ, Yekrats, ZamorakO o, Ziphon, आशीष भटनागर, 477anonymous edits

Colorfulness  Source: http://en.wikipedia.org/w/index.php?oldid=452048885  Contributors: Aboalbiss, Adelpine, Adoniscik, Arcadian, Aude, Casey56, Conscious, CoyneT, DA3N, Dicklyon,Duoduoduo, Ettrig, Frietjes, Fryed-peach, Green Heart 1985, HappyLogolover2011, Interiot, Jacobolus, Keraunos, Lefty, MeekSaffron, Michael Hardy, MisterSheik, Morecambe1, Natebw,Neilbeach, Night Gyr, Nikai, Ohnoitsjamie, Paul August, Peter G Werner, Radagast83, Rjwilmsi, Rmhermen, Roke, Semolina Pilchard 67, Sims2uni, SmileToday, Sonjaaa, Specious, Spitzak,Srleffler, Svick, Tagishsimon, TallNapoleon, Tsiaojian lee, VMS Mosaic, VivaEmilyDavies, Waldir, Wapcaplet, Welsh, Wiki Raja, Wmhawth, Ylai, 45 anonymous edits

Dichromatism  Source: http://en.wikipedia.org/w/index.php?oldid=460852026  Contributors: Dmmaus, Eidako, Finog, Fotaun, FrankFE, Jfdwolff, Krefts, Mild Bill Hiccup, Natevw, Rjwilmsi,Scentoni, Srleffler, Woohookitty, 11 anonymous edits

Hue  Source: http://en.wikipedia.org/w/index.php?oldid=461677575  Contributors: (3ucky(3all, AED, Abdull, Aboalbiss, AugPi, BazookaJoe, Bogey97, CL, ChazYork, Chinasaur, Chipcoi1089,Creidieki, Crohnie, DHN, Darth Panda, Deb, DemonThing, Denelson83, Dicklyon, Discospinster, Dyaka, Eshmo, Fanghong, Forelisevn, FrozenMan, Fryed-peach, GandalfDaGraay, Gogo Dodo,Graham87, Hanoipeacetour, Hans Dunkelberg, Hart37, JHunterJ, Jacobolus, Jimp, Joelr31, JohnManuel, Jppellet, Keraunos, Lefty, LittleHow, Loren.wilton, Lovibond, Lulu noodle93,Lumpbucket, MJ94, Magioladitis, Magnus Manske, Maksim-e, Mav, Mbubel, Mmh, Mormegil, NOrbeck, Nbarth, NekoDaemon, Neutrality, Nono64, Northumbrian, Olivier, Ost316,Oxygene123, P. B. Mann, PJV, Pak21, Picaroon, Pietaster, Prohlep, Rabidtommy, RandomXYZb, RedAndr, Regenspaziergang, RitKill, Rjwilmsi, Rocket71048576, Rogper, Roke, Runefrost,Ryanmcdaniel, S h i v a (Visnu), Sander123, Sgkay, Srleffler, SteinbDJ, Stevertigo, Suran.c, The Thing That Should Not Be, TheGiantHogweed, ThingXYZ, Thorseth, Tkgd2007, Tumblingsky,VMS Mosaic, Vanished User 8a9b4725f8376, Vardion, VernoWhitney, Wapcaplet, Wernervb, 106 anonymous edits

Tints and shades  Source: http://en.wikipedia.org/w/index.php?oldid=457670098  Contributors: 23funnel23, Aboalbiss, Adelpine, Alansohn, Anna, Avoided, Dhynbaa, Download, Grey Maiden,Impy4ever, Jacobolus, James.Denholm, Jeff G., Jk2q3jrklse, Keraunos, Malkinann, Martinship, Meco, Robofish, VMS Mosaic, Xanzzibar, පසිඳු කාවින්ද, 40 anonymous edits

Lightness  Source: http://en.wikipedia.org/w/index.php?oldid=441181108  Contributors: Aboalbiss, Adelpine, Adoniscik, Chris the speller, Cpoynton, Dicklyon, Drbreznjev, Fatheroftebride,Fryed-peach, Jacobolus, Jauhienij, Just plain Bill, Keraunos, McSush, Neparis, Ost316, P.B. Pilhet, Pegship, Rich Farmbrough, Ru dagon, SharkD, Srleffler, Svick, The Random Editor, 19anonymous edits

Opponent process  Source: http://en.wikipedia.org/w/index.php?oldid=452813016  Contributors: Adoniscik, Ancheta Wis, Anglo-Araneophilus, Benandorsqueaks, Bluemoose, Chinze, Delldot,Dicklyon, Duoduoduo, Everyking, False vacuum, Forbsey, Geoemyda, Georgia guy, Ghinessk, Jacobolus, Johnrpenner, KSmrq, Kcordina, Ketiltrout, Loren.wilton, MWAK, Magiciandude,Michael Hardy, Mijelliott, NekoDaemon, Nono64, Poodle slyr, Quibik, Sean.hoyland, Spooky, Uaxuctum, Uncle G, Waiting4beckett, Wragge, Wyatt915, 51 anonymous edits

Impossible colors  Source: http://en.wikipedia.org/w/index.php?oldid=464687095  Contributors: AaRH, Aaron Kauppi, Anthony Appleyard, Auric, Cate, Crazymonkey1123 public, Da5nsy,Davidhorman, Duoduoduo, Gioto, Goustien, Itchesavvy, Jpgordon, Koavf, Lova Falk, Metallaxis, Michael Hardy, Mikechen, Mmoople, MrBurns, NisseSthlm, OrangeDog, Rhubbarb,Spinningspark, Tom Piantanida, VMS Mosaic, Wanderer32, Welshie, WryVendor, Wyatt915, XP1, Ysangkok, Zuchinni one, 19 anonymous edits

Color vision  Source: http://en.wikipedia.org/w/index.php?oldid=464652494  Contributors: 1993kid, A314268, AED, Abeg92, Aboalbiss, Acalamari, Adoniscik, AdvCentral, AgentPeppermint,AlanUS, Angela, Anihl, Aoleson, Aranae, Arcadian, Archer7, Arthena, Atarr, Atlant, Azcolvin429, BIGELLOW, Batintherain, Beland, Belovedfreak, BenFrantzDale, BenRG, Bmju, Bobo192,Bookandcoffee, Britonamission, C A Morris, C.Fred, Calmer Waters, Caribant, Cgingold, Chris the speller, Codeye, Crystallina, Cyrius, D, D3z, Daltonsgirl, Daqu, Delldot, Dicklyon, Dkroll2,Donarreiskoffer, Dondegroovily, Dpv, Drag-5, Drj11, Duoduoduo, DynamoDegsy, Dysmorodrepanis, Ec5618, Edison, Efodix, Emperorbma, Enisbayramoglu, Ericmelse, Feitosa-santana, FredHsu, Gadfium, Gene Nygaard, Georgia guy, Graft, Guidod, Guillep2k, Guyburns, HallucigeniaUK, Hankwang, Harryboyles, Headbomb, Hgold, Hunt9, IceKarma, Imagine1989, Iridescent,Jackhynes, Jacobolus, Janke, Jerry, Jhenderson777, Joe Decker, Johnkarp, Johnor, Jonas August, Jonverve, Joriki, JukeJohn, JunCTionS, Kazvorpal, Keegan, Keraunos, Kinema, KoenB, LAX,Last Avenue, Lcguang, Lepidoptera, Little Mountain 5, LittleHow, Logical Fuzz, LtPowers, Lucasilver, Magioladitis, Magister Mathematicae, MartinPoulter, McGeddon, Medtopic, Mfwitten,MichaelMcGuffin, Micromaster, Minesweeper, Moonksy29, Munawar6, Nakon, Natrij, Nbarth, NekoDaemon, NifCurator1, Noetica, NotAnonymous0, Notinasnaid, Nuvitauy07, OlivierHammam, Orderud, Oscabat, Ost316, Owen, OwenX, PAR, PatrickFisher, Persian Poet Gal, Picus viridis, Pmineault, Pmronchi, Psheno, Psychron1, QuentinUK, Quota, RDBrown,ReallyNiceGuy, Rebornsoldier, Rechlin, Renatops, Rich Farmbrough, Richard001, Richerman, Rjwilmsi, Robertg9, SF007, Sanya3, Sayeth, Sbharris, Scwlong, Seabhcan, Sean.hoyland, Seglea,Selket, Shadowjams, SharkD, Shepaado, Sjöðar, Skatebiker, Smack, Smith609, Spigget, Srleffler, Suffusion of Yellow, SvenAERTS, Tagal, TaintedMustard, Talon Artaine, Tckma, The ThingThat Should Not Be, TheMindsEye, Thorseth, Threetwoone, Titoxd, Tom Lougheed, Tom harrison, Tyler, Usien6, VMS Mosaic, Vanessaezekowitz, Vaughan Pratt, Voidxor, Vsmith, Wandell,Washington00, Wernervb, Willhsmit, Wotnow, Zarnivop, Zink Dawg, 235 anonymous edits

Visual perception  Source: http://en.wikipedia.org/w/index.php?oldid=464299206  Contributors: (, A314268, A4, AED, Abqwildcat, Accuruss, Adrian.benko, Alexander Maier, Alexandrov, Alexis.rodet, Anatoly IVANOV, Ancheta Wis, Andre Engels, Andreas Kaufmann, Andross52, Angela, Antony-22, Applesnnbananas, Arcadian, Arfgab, ArglebargleIV, Argumentum ornithologicum, Ashwin73, Audiovideo, AwamerT, BD2412, Bad Romance, Beland, BenFrantzDale, Bensaccount, Bentogoa, BirgitteSB, Blue520, Bmju, Boing! said Zebedee, Brandon, Bstephens393, CP\M, CanadianLinuxUser, Cgingold, Cleancleaner, Cogpsych, Cooper24, Cralize, CzarNick, Danger, Darrenhusted, David Latapie, David-Sarah Hopwood, Dbfirs, DerHexer, Diberri, Dilcoe, Dontaskme, Dpv, Duja, Duncan, Dycedarg, Ec5618, EdH, Eekerz, Eijiaj80, EinderiheN, Eliyak, Emariatos, Everyking, Factfinderz, Famousdog, Fastfactchecker, Fenton1234, FlyHigh, Fratrep, FreplySpang, Furrykef, Gary King, Geeoharee, Geraldfird, Giftlite, Gilsatron, Gioto, Glenn, Gludwiczak, Graft, GreenLocust, Greg.collver, Grutness, Gunza, Gurch, H2g2bob, Halmstad, Hans-Werner34, Hazel77, HieronymusGuinevere, Historychecker, Hordaland, IRP, Immunize, Infinitejpower, Insanity Incarnate, Intangir, Intromission, Ixfd64, J04n, Jacobolus, Jagged 85, Janviermichelle, Jess523s, Jj1236, Joe yeeha, Johnkarp, Jtkiefer, KYN, Kathy usui, Kfsung, LEMEN, Landroving Linguist, Lars Washington, Leranedo, Lizaahle, LjL, Lochaber, Looie496, Lussmu, Mac, MajorVariola, Mario1337, MarkSutton, MarnetteD, Martin Kozák, MartinPoulter, MarylandArtLover, MassimoAr, Mattisse, Matusz, Mdd, Medtopic, Meegs, Mentifisto, Merovingian, Michael Hardy, Midnightcomm, Mild Bill Hiccup, Mindmatrix, Mjr Armstrong, Mlessard, Modulatum, MortimerCat, MrOllie, MuZemike, Mukadderat, Naddy, NawlinWiki, Neostinker, Nerrolken, Neuropsychology, Never give in, Nick, Nk, Noetica, Novem Linguae, Nuvitauy07, ObfuscatePenguin, PLA y Grande Covián, Parkjunwung, Patrick, Pedant, Perfect Proposal, Peter T.S., Peterlin, Petter Trillkott, PhilHibbs, Pizza Puzzle, Pleasantville, Poetaris, Pollinosisss, Poshzombie, Privong, Psychron1, RSaunders, RadioElectric, Ragesoss, Rarara1111, Raudys, Richard001, Rimtect, Roadnottaken, Robertg9, Rokers, RoyBoy, RyanCross, Sacre, Sadi Carnot, Sango123, Sanya3, Sardanaphalus, Sbarthelme, Sbluen, Scathane, Seabhcan, Seeyou, Selket, Sephiroth BCR, Sfan00 IMG, Snoyes, SoCal, Solipsist, Soundray, Sparkleyone, Speed8ump, SpeedyGonsales, Spencerk, Srenee91, StealthB, Steve Pucci, Strasburger, Svick, Swanav, Tango, Tangotango, Template namespace initialisation script, Tevildo, Tharshikatee, The Anome, The Magnificent Clean-keeper, Thebigone45, Themfromspace, Thesoxlost, Thetoothpick, Thingg, Thongsftw, Tierlieb, Tobby72, Tony1, Twinsday, Tó campos, Utcursch, Vaughan, Verne Equinox, Vsion, Vssun, Wakebrdkid, Waterfall117, Werdan7, West.andrew.g, Where next Columbus?, White Trillium, Wildkoala, William M. Connolley, Wolfdog, Woohookitty, Worldbookman, X96lee15, Xevi, Xyoureyes, Yidisheryid, Ylem, Zephy2034, Περίεργος,

Article Sources and Contributors 112

318 anonymous edits

List of colors  Source: http://en.wikipedia.org/w/index.php?oldid=464868562  Contributors: 041744, 15thWardWestBank, 220 of Borg, 4twenty42o, AGK, Abb615, Abcdefg987654, Abce2, AceETP, Addshore, Adreantruth, Adrey, Aeron Valderrama, Aesopos, Agesilaus II, AgnosticPreachersKid, Ahoerstemeier, Ahonc, Airplaneman, Aitias, Aksi great, AlanBarrett, Alansohn, Alexkin,Alexzabbey, Alpha Ralpha Boulevard, Alsandro, Altenmann, Altermike, AmericaIsNumberOne, Andrea105, Andros 1337, Andux, AngelOfSadness, Angelofdeath275, Anonymous Dissident,Antandrus, Antique Rose, Apparition11, Arch dude, Ardric47, ArglebargleIV, Arthena, Arxiloxos, Asciic, Asdfjklqazse, Ashishbhatnagar72, Atomicharcoal, Avoided, B58PMCSA,Backpackadam, Bagatelle, Barrelbabe3737, BarretBonden, Bart133, Baseball Bugs, Blue520, Bluedenim, Bluenectarine, Bobo192, Bobrayner, Brainsurge33, Bucketsofg, Bumm13,Burndownthedisco, Burntpiecrust, Bus stop, Butros, CUSENZA Mario, CWii, Cacums, Cait1208, Calmer Waters, Camw, Canterbury Tail, Canthusus, Capedia, Capricorn42, Captain Virtue,Captain panda, Catgut, Cathyahn, Ccson, Centrx, Cerebralpayne, Cgmusselman, Charles Matthews, Charlottelai, Chaser, Chasingsol, Chienlit, Chris the speller, Christian75, Chuunen Baka,Circeus, Closedmouth, Cntras, ColinBoylett, Comedy Dan, Coopdawg7533, Coopkev2, Corington, Corvus cornix, Coryknick, Courcelles, CoyneT, Crazy Boris with a red beard, Creidieki,Crissov, Crocodealer, Crohnie, CrowzRSA, Cspenc36, Ctachme, Cubs Fan, CyberSkull, Cyberkid ua, D2513850, DARTH SIDIOUS 2, DJ Clayworth, DMacks, DRTllbrg, DVdm, DaDoc540,Darrien, Darth Newdar, David0811, Davidbod, Davish Krail, Gold Five, Dbenbenn, Dbfirs, Dbritnell, Dcljr, DeC, DeWayne, Dekisugi, Denelson83, Denisarona, Dicklyon, Digfarenough,DiplomBastler, Dirjarmocksorz, Discospinster, Divide, Djaychela, Docu, Dodo's Conundrum, Donarreiskoffer, Donfbreed, Draco, Drilnoth, Dude1818, Dureo, E2eamon, ESkog, Eaglemach,Ebyabe, Eeekster, Eequor, Ehrenkater, Elevenzeroone, Emnat, Emrrans, Epbr123, Excirial, Extra999, Fabrizio.sporchia, Falcon8765, FastLizard4, Feinoha, Festyzizzle, Finalius, Fish and karate,FisherQueen, Flewis, Fluffernutter, Fluiday, Foobaz, Fran Rogers, FreplySpang, Frietjes, Friginator, Frigotoni, From Selma to Stonewall, Funandtrvl, Funnyfarmofdoom, Fëaluinix, GabrielF,Gail, Garnerguy123, Geahanse, Gene Nygaard, Geodog242, George Hernandez, Georgia guy, Glenn L, Gogo Dodo, Gojistomp, Gracenotes, GrayFullbuster, Groat, Grunt, Gtrmp, Guoguo12, GusPolly, Gwernol, HJ Mitchell, Halfway to never, Hammersoft, HappyInGeneral, Happysugarrush, Harkenbane, Hasek is the best, Hayabusa future, Heatseeker0, Heegoop, Henning Makholm,Hermitage17, Heron, Hmrox, Hongking, Hqb, Husond, IAmTheCoinMan, IW.HG, Ididntrecognizethatlastepisode, Igoldste, Ihateakiva, Ijstmariedashton, IlyaHaykinson, Immunize, Imroy,IncognitoErgoSum, Indon, Ionistii, IronGargoyle, ItsZippy, Itsyourmom, IwantNapalm, Ixfd64, J. Naven, J.delanoy, JForget, JV Smithy, Ja 62, JaGa, Jaberwocky6669, Jack Merridew, Jackol,Jacobolus, Jagginess, Jak123, JamieS93, Jebus0, Jeepday, Jeff G., JeremyA, Jeromesyroyal, JesusAddict3791, Jhenderson777, Jimp, Jj.pitrelli, Jklin, Jmlk17, Jncraton, John Anderson, John254,Jojit fb, Joseph Solis in Australia, Josephycc, Jurema Oliveira, Jusjih, JustAGal, KJBracey, Kafka Liz, Kballigator4, Kenkku, Keraunos, Kesac, Kevinkor2, Kilo-Lima, Kingpin13, Kingturtle,Kintetsubuffalo, Klausness, Klingac, KoG Iceman, Koavf, Kobayashis, Korax1214, Krishvanth, Kruusamägi, Kudret abi, Kuru, Kwamikagami, Kyle1278, Kylet, Kyorosuke, L Kensington,LAPS, La Pianista, Lacrymocéphale, Latina Ashburg, Latitude0116, Launchballer, Laura S, Lax4mike, Lchiarav, Leafyplant, Lee J Haywood, Lee15482, Lefty, Lesnail, Liastnir, Libcub, Lights,Lironos, Locke Cole, Logdick, Lollipopluver415, Loopla, Luffyzors, Luk, LunchBox5181, MCTales, MPF, Mabdul, MacMan2626, Macy, Maethordaer, Mahewa, Majorly, Mandarax, Mani1,Marasama, Marauder40, Marek69, MarnetteD, Martarius, Mastershake phd, Mathel, Mathratio, Matt Deres, Mcmillin24, Mdebets, MelSkunk, MementoVivere, Meningitis888, Mephistophelian,Merovingian, Michel BUZE, Mike Rosoft, Mike902, Mild Bill Hiccup, Mindmatrix, Minesweeper.007, MiracleMat, Mit-aizama, Mitchazenia, Mjquinn id, Modernist, Monsieurdl, Monster boy1,Montana's Defender, Moonriddengirl, Moony103, Morwen, MrDolomite, Mtking, Mxn, My76Strat, Mário, N5iln, NHJG, NHRHS2010, Naep1, Naggers, Nahum Reduta, Nakon, Nameneko,Naryathegreat, Nascar1996, NawlinWiki, NellieBly, Nemen32, Nepfabcd, Nesnad, Netalarm, Nezzadar, Nguyenthephuc, Night of the Big Wind, Nkocharh, Noah22, Noleander, Norbu,Notinasnaid, Nuberfuzzy, OlEnglish, Oliver202, Oms1005, Onorem, Orangemike, Orphan Wiki, Oxymoron83, PPWen, PacMan1980, Paepaok, PaleAqua, Pan Camel, ParisianBlade, Patkwok,Pax85, Peterxdeng, Phil Boswell, Phil Bridger, Philip Trueman, Picaroon, Pinethicket, Pip2andahalf, Pjhofmann, Plastikspork, Poeloq, Ppanzini, Praefectorian, ProtoFire, Psychonaut,Pufferfish101, Puppy132, Pyfan, Qajar, Quantumobserver, QuartierLatin1968, Quiddity, Qxz, RL0919, Radioactive afikomen, Rambam rashi, Rbanzai, Rdococ, Reaper Eternal, Recognizance,Redfarmer, Redvers, Renzut, Retiono Virginian, RexNL, Rholton, Rich Farmbrough, Richard-of-Earth, RichardF, Rigadoun, Riggr Mortis, Rikkus, Rjwilmsi, Rlendog, Roberta F., Rochelimit,Roland Richter, RoseCherry, Rowman, Rrburke, Rreagan007, Rror, Rsduhamel, Ruby Emo, Ryan Taylor, Ryanmcdaniel, Ryulong, SJP, SRFFGT, Saccerzd, Saimhe, Saturday, Scarce,Scmaruthi, ScottAlanHill, Scribble Monkey, Secret Saturdays, Shanes, Shazzam32, Shd, Shell Kinney, Shervinemami, Shosetsuka, Shyamthirumalai, Siddhant, Sigma 7, Silivrenion,Simtropolitan, Sionus, Skweltch, SkyWalker, Slightsmile, Slon02, Smurrayinchester, Socal gal at heart, Some jerk on the Internet, Someoneinmyheadbutit'snotme, Spanglej, Sphilbrick, Splash,SportsMaster, Squirepants101, Srleffler, Starfarmer, Steven Zhang, Storm Rider, Strdst grl, SuperHamster, Sven Manguard, Swmnjen3, Synchronism, TAnthony, THEN WHO WAS PHONE?,TUF-KAT, Tajik24, Tassedethe, Tbhotch, TeaDrinker, Tempodivalse, TenPoundHammer, The High Fin Sperm Whale, The Midna, The Missing Piece, The Thing That Should Not Be, The Tom,The editor1, Thecheesykid, Theme97, Thingg, Thisisborin9, Thisisbossi, Thomas Kelly, Thue, Tide rolls, Tnxman307, Toddst1, Tohd8BohaithuGh1, Tommy2010, Tonkun, Tonywalton, TreeBiting Conspiracy, Trialsanderrors, Trivialist, Troyheidenberg, True Pagan Warrior, Trusilver, TutterMouse, Tyrol5, UU, Uncle Dick, Usb10, Useight, Utcursch, VMS Mosaic, Vanished6551232, Vanished user 39948282, Vectro, Velella, Verbalise, Verdy p, Vicarious, Vishvax, Voxii, WLU, Waldir, Wavelength, Waymorecreative, Wayne Miller, Wayne Slam, Wetman,WiKinny, Wiikipedian, WikHead, Wiki alf, WikiY, Wikipelli, Wildoneshelper, WillDarlock, Willking1979, Wknight94, Wolfforlife40, Woudloper, Wpell, Wtmitchell, Wzwz, Xinyu, Xkonax,Xyzzy n, Yacht, Yun-Yuuzhan (lost password), Yurymik, Zappa711, Zaui, Zephyr103, Zhatt, Zoe, Zombie Hunter Smurf, Zondor, ZooFari, Zzyzx11, Ødipus sic, Саша Стефановић, 金肅, 2973anonymous edits

Web colors  Source: http://en.wikipedia.org/w/index.php?oldid=464211513  Contributors: 4myself4, A000040, ABF, Aapo Laitinen, Addionne, AerisMTW, Akuchling, Alan Liefting,AlistairMcMillan, Alsandro, Altermike, Andrejj, AndrewWTaylor, Andrewpmk, Angelo, Angr, Anonymous Dissident, Apoc2400, Arbitrarily0, Army1987, Arnon Chaffin, Ashishbhatnagar72,Atomician, Ayrton Prost, Badgernet, Bewildebeast, Bjankuloski06en, Bloodpack, Blow of Light, Bluedenim, Bobo192, BorgQueen, Btipling, CUSENZA Mario, CattleGirl, Causesobad, CesarB,ChristTrekker, Christopher Parham, CloudStrife, Codingmasters, CoyneT, Crissov, Crohnie, Ctachme, CyberSkull, Cyp, Damian Yerrick, Damieng, Danthorpe2002, Daveswagon, DavidBiddulph, David Gerard, David Kernow, Dbreakey, Den fjättrade ankan, Denelson83, Denisutku, Deryck Chan, Dicklyon, Discospinster, Donarreiskoffer, DougsTech*com, Dxhtml, Dysprosia,Ed g2s, Edgepedia, Edokter, Efa, ElTchanggo, Eleveneleven, Ellywa, Elphion, Escape Orbit, Excirial, EyeSerene, Fabartus, Fanghong, Farsouth, FastLizard4, Fieldday-sunday, Finbarr Saunders,Flashmorbid, Fluffernutter, Franci.kapel, Fresheneesz, FuriousFreddy, Furrykef, G Allegre, Gelo71, Geni, Giftlite, GizmoRay, Glenn L, Gobonobo, Googlere, Gordeonbleu, Groovybreadstick,Gus Polly, Gwillhickers, Hadal, HaeB, Hang Li Po, Hardwick, Hawky, Heegoop, Henry Flower, HereToHelp, Heron, Hightilidie, Hja, Hopper-blackrose, Hossen27, Howard the Duck, Hu12,Husond, Hyad, Hydrargyrum, ILovePlankton, Ian Fieggen, Indefatigable, Ipatrol, Itsyourmom, Ixfd64, J.delanoy, JECompton, JWB, Jamelan, JanineR, Janke, Jeromesyroyal, Jhenderson777,Jimp, Jleedev, Jmh, Jmlk17, Jonathan W, Jonwoolley, Jor, Jsjunkie, Jtneill, Keraunos, Kim Bruning, Kjoonlee, Ksy92003, LOL, La Pianista, Launchballer, Leandrod, Lights, Linguisticsstud,Logoorange, Lowellian, Luk, LunaticBeatnik, M.O.X, Madpilot, MahaPanta, Mani1, Manop, Maquiguy, Martarius, Matt Yeager, MattGiuca, MaxHund, MeStinkBAD, Menchi, Mepolypse,MetaManFromTomorrow, Mindmatrix, Mobykanuno, Monster boy1, MonteShaffer, Moondyne, Moopstick, Mouse is back, Mr.Z-man, MrDolomite, MrOllie, Ms2ger, Mulad, Mun206, Mutinus,NantonosAedui, Nein, NekoDaemon, NewEnglandYankee, Nickshanks, Nigelj, Nikola Smolenski, Nilfanion, Notinasnaid, Nwwaew, Oaktwig, OhanaUnited, Ohnoitsjamie, OlEnglish,Omniplex, PC78, PaleAqua, Patrick, Paul A, Paul August, Pax:Vobiscum, Perey, Peruvianllama, Phil Boswell, PhilHibbs, Philip Trueman, Pi is 3.14159, Pipatron, Pixeltoo, Pixi,PizzaMargherita, Pnm, PointedEars, Pomte, PopeButtercockXIV, Power Slave, Prodego, Psychonaut, Quiddity, Rbucci, Rebornsoldier, Reddi, Rehnn83, Reisio, Renice, RespekT, RicardoCancho Niemietz, Rich Farmbrough, Richard D. LeCour, Richard75, RichardF, Rick Cooper, RobertG, Robwingfield, Ropers, RoyBoy, Ruakh, Rursus, Salam32, Samw, Scapler, Scjessey, Sebaz86556, Seidenstud, Sentience, Serevinus, Shadowjams, Shanes, Shepazu, Signalhead, Simetrical, SimonDeDanser, Smalljim, Sodaplayer, Sophie, Stephenj642, Stormie823, Strcat, Sumirp,SunCountryGuy01, Superm401, Svick, Swagger28, Syp, Takai003, TastyPoutine, The Anome, The Mysterious El Willstro, The Thing That Should Not Be, The editor1, Tholly, Tilankar,Timothy Clemans, Trainra, Traxs7, Tristanb, Turlo Lomon, Twentydragon, Uannis, Ugur Basak, VMS Mosaic, Verdy p, Victor Engel, Vipinhari, W1tgf, WODUP, Waldir, Wapcaplet,Warlordwolf, Wayne InSane (Of RTC), Wayne Slam, Werdan7, Wertuose, WhatamIdoing, Whytecypress, Wikitonic, XaeL, Xiong, Ybenharim, Yugsdrawkcabeht, ZimZalaBim, Zoicon5,Zollerriia, Zundark, 415 anonymous edits

Image Sources, Licenses and Contributors 113

Image Sources, Licenses and ContributorsFile:Colouring pencils.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Colouring_pencils.jpg  License: Creative Commons Attribution-Sharealike 3.0  Contributors: MichaelMaggsImage:Rendered Spectrum.png  Source: http://en.wikipedia.org/w/index.php?title=File:Rendered_Spectrum.png  License: Creative Commons Attribution-Sharealike 3.0  Contributors: SpiggetFile:Optical grey squares orange brown.svg  Source: http://en.wikipedia.org/w/index.php?title=File:Optical_grey_squares_orange_brown.svg  License: Public Domain  Contributors:user:JunCTionS (based on source)File:Cones SMJ2 E.svg  Source: http://en.wikipedia.org/w/index.php?title=File:Cones_SMJ2_E.svg  License: Creative Commons Attribution-Sharealike 3.0,2.5,2.0,1.0  Contributors: Originaluploader was Vanessaezekowitz at en.wikipedia. Later version(s) were uploaded by Dicklyon, BenRG at en.wikipedia.File:1Mcolors.png  Source: http://en.wikipedia.org/w/index.php?title=File:1Mcolors.png  License: Public Domain  Contributors: JankeFile:Ventral-dorsal streams.svg  Source: http://en.wikipedia.org/w/index.php?title=File:Ventral-dorsal_streams.svg  License: Creative Commons Attribution-ShareAlike 3.0 Unported Contributors: Javier Carro, Lokal Profil, Selket, Was a beeFile:Afterimage.svg  Source: http://en.wikipedia.org/w/index.php?title=File:Afterimage.svg  License: Public Domain  Contributors: Me (Stevo-88)File:CIExy1931 fixed.svg  Source: http://en.wikipedia.org/w/index.php?title=File:CIExy1931_fixed.svg  License: Creative Commons Attribution-Sharealike 2.5  Contributors: CIExy1931.svg:Sakurambo derivative work: BenRG (talk)Image:Colorspace.png  Source: http://en.wikipedia.org/w/index.php?title=File:Colorspace.png  License: Attribution  Contributors: Original uploader was Cpesacreta at en.wikipediaFile:RGB and CMYK comparison.png  Source: http://en.wikipedia.org/w/index.php?title=File:RGB_and_CMYK_comparison.png  License: Public Domain  Contributors: RGB_CMYK_4.jpg:Annette Shacklett derivative work: Marluxia.Kyoshu (talk)Image:AdditiveColor.svg  Source: http://en.wikipedia.org/w/index.php?title=File:AdditiveColor.svg  License: Public Domain  Contributors: Original uploader was SharkD at en.wikipedia Laterversions were uploaded by Jacobolus at en.wikipedia.Image:SubtractiveColor.svg  Source: http://en.wikipedia.org/w/index.php?title=File:SubtractiveColor.svg  License: Public domain  Contributors: Original uploader was SharkD at en.wikipediaLater version uploaded by Jacobolus, Dacium at en.wikipedia.Image:GoetheFarbkreis.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:GoetheFarbkreis.jpg  License: Public Domain  Contributors: Goethe, via Prof. Dr. Hans IrtelImage:Munsell-system.svg  Source: http://en.wikipedia.org/w/index.php?title=File:Munsell-system.svg  License: Creative Commons Attribution-Sharealike 3.0  Contributors: Jacobolus,Mahlum, WikipediaMaster, 1 anonymous editsFile:Chevreul's RYB chromatic diagram.png  Source: http://en.wikipedia.org/w/index.php?title=File:Chevreul's_RYB_chromatic_diagram.png  License: Public Domain  Contributors:Benjamin Stillman after ChevreulImage:Color star-en.svg  Source: http://en.wikipedia.org/w/index.php?title=File:Color_star-en.svg  License: GNU Free Documentation License  Contributors: Al2Image:Black-body-in-mireds-reversed.png  Source: http://en.wikipedia.org/w/index.php?title=File:Black-body-in-mireds-reversed.png  License: Public Domain  Contributors: AdoniscikImage:RGB illumination.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:RGB_illumination.jpg  License: GNU Free Documentation License  Contributors: en:User:Bb3cxvImage:Tartan Ribbon.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Tartan_Ribbon.jpg  License: Public Domain  Contributors: James Clerk Maxwell (original photographic slides); scan by User:Janke.Image:J C Maxwell with top.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:J_C_Maxwell_with_top.jpg  License: Public Domain  Contributors: Original uploader was Dicklyon aten.wikipediaImage:Duhauron1877.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Duhauron1877.jpg  License: Public Domain  Contributors: Louis Ducos du Hauron (1837 – 1920)Image:BYR color wheel.svg  Source: http://en.wikipedia.org/w/index.php?title=File:BYR_color_wheel.svg  License: GNU Free Documentation License  Contributors: Original uploader wasSakurambo at en.wikipediaImage:Prisme.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Prisme.jpg  License: Public Domain  Contributors: Adoniscik, Ranveig, Teebeutel, W!B:Image:Additive color mixing simulated.png  Source: http://en.wikipedia.org/w/index.php?title=File:Additive_color_mixing_simulated.png  License: Public Domain  Contributors: PkoImage:SubtractiveColorMixing.png  Source: http://en.wikipedia.org/w/index.php?title=File:SubtractiveColorMixing.png  License: GNU Free Documentation License  Contributors: Adoniscik,Mormegil, Pamri, Quark67, 1 anonymous editsImage:CRT phosphors.png  Source: http://en.wikipedia.org/w/index.php?title=File:CRT_phosphors.png  License: GNU Free Documentation License  Contributors: Original uploader wasDeglr6328 at en.wikipediaimage:AdditiveColor.svg  Source: http://en.wikipedia.org/w/index.php?title=File:AdditiveColor.svg  License: Public Domain  Contributors: Original uploader was SharkD at en.wikipedia Laterversions were uploaded by Jacobolus at en.wikipedia.Image:CIE1931xy sRGB.svg  Source: http://en.wikipedia.org/w/index.php?title=File:CIE1931xy_sRGB.svg  License: Public Domain  Contributors: BenRGImage:CIE1931xy CIERGB.svg  Source: http://en.wikipedia.org/w/index.php?title=File:CIE1931xy_CIERGB.svg  License: Public Domain  Contributors: BenRGimage:SubtractiveColor.svg  Source: http://en.wikipedia.org/w/index.php?title=File:SubtractiveColor.svg  License: Public domain  Contributors: Original uploader was SharkD at en.wikipediaLater version uploaded by Jacobolus, Dacium at en.wikipedia.File:Opponent colors.svg  Source: http://en.wikipedia.org/w/index.php?title=File:Opponent_colors.svg  License: Creative Commons Attribution-ShareAlike 3.0 Unported  Contributors:User:SpookyImage:Surfing in Hawaii unmodified.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Surfing_in_Hawaii_unmodified.jpg  License: Public Domain  Contributors: Cpl. Megan L.Stiner, sRGB profile added by Jacob RusImage:Surfing in Hawaii+50 LCh chroma.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Surfing_in_Hawaii+50_LCh_chroma.jpg  License: Public Domain  Contributors: Cpl.Megan L. Stiner, modified by Jacob RusImage:Surfing in Hawaii+50 saturation.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Surfing_in_Hawaii+50_saturation.jpg  License: Public Domain  Contributors: Cpl. MeganL. Stiner, modified by Dick Lyon and Jacob RusImage:Surfing in Hawaii L* channel.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Surfing_in_Hawaii_L*_channel.jpg  License: Public Domain  Contributors: Cpl. Megan L.Stiner, sRGB profile added by Jacob RusImage:saturationdemo.png  Source: http://en.wikipedia.org/w/index.php?title=File:Saturationdemo.png  License: Public Domain  Contributors: Lefty (2006-03-04), inspired by Coyne Tibbets(CoyneT), 03/18/2005Image:Excitation Purity.svg  Source: http://en.wikipedia.org/w/index.php?title=File:Excitation_Purity.svg  License: Creative Commons Attribution-ShareAlike 3.0 Unported  Contributors:adoniscikImage:Dichromatism.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Dichromatism.jpg  License: Public Domain  Contributors: KreftsImage:HueScale.svg  Source: http://en.wikipedia.org/w/index.php?title=File:HueScale.svg  License: Public Domain  Contributors: w:ru:User:KalanImage:Hue shift six photoshop.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Hue_shift_six_photoshop.jpg  License: GNU Free Documentation License  Contributors: Akinom,Roke, WikipediaMasterImage:Hue.gif  Source: http://en.wikipedia.org/w/index.php?title=File:Hue.gif  License: Public Domain  Contributors: U.S. National Park Service (raw image), modified by en:user:(3ucky(3allImage:HSV cone.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:HSV_cone.jpg  License: GNU Free Documentation License  Contributors: Created by WapcapletImage:HSV-RGB-comparison.svg  Source: http://en.wikipedia.org/w/index.php?title=File:HSV-RGB-comparison.svg  License: Creative Commons Attribution-ShareAlike 3.0 Unported Contributors: en:user:GoffrieImage:tint-tone-shade.svg  Source: http://en.wikipedia.org/w/index.php?title=File:Tint-tone-shade.svg  License: Public Domain  Contributors: JacobolusImage:Kleurenovergang van zwart naar blauw.png  Source: http://en.wikipedia.org/w/index.php?title=File:Kleurenovergang_van_zwart_naar_blauw.png  License: Creative CommonsAttribution-ShareAlike 3.0 Unported  Contributors: Original uploader was Wilinckx at nl.wikipediaImage:HSLSphere.svg  Source: http://en.wikipedia.org/w/index.php?title=File:HSLSphere.svg  License: Creative Commons Attribution-Share Alike  Contributors: SharkDImage:ColorValue.svg  Source: http://en.wikipedia.org/w/index.php?title=File:ColorValue.svg  License: GNU Free Documentation License  Contributors: ColorValue.jpg: Mahlum derivativework: McSush (talk)

Image Sources, Licenses and Contributors 114

Image:Lightness approximations.svg  Source: http://en.wikipedia.org/w/index.php?title=File:Lightness_approximations.svg  License: Creative Commons Attribution-Sharealike 2.5 Contributors: LovibondImage:Opponent colors.svg  Source: http://en.wikipedia.org/w/index.php?title=File:Opponent_colors.svg  License: Creative Commons Attribution-ShareAlike 3.0 Unported  Contributors:User:SpookyFile:Color perception.svg  Source: http://en.wikipedia.org/w/index.php?title=File:Color_perception.svg  License: Public Domain  Contributors: Wyatt915File:yelue.svg  Source: http://en.wikipedia.org/w/index.php?title=File:Yelue.svg  License: Public Domain  Contributors: Wyatt915File:Psychophysical.svg  Source: http://en.wikipedia.org/w/index.php?title=File:Psychophysical.svg  License: GNU Free Documentation License  Contributors: Psychophysical.jpg: Originaluploader was Dkroll2 at en.wikipedia derivative work: Vanessaezekowitz (talk)File:Filterstef.JPG  Source: http://en.wikipedia.org/w/index.php?title=File:Filterstef.JPG  License: GNU Free Documentation License  Contributors: User Stefan.lila on sv.wikipediaFile:Cone-fundamentals-with-srgb-spectrum.svg  Source: http://en.wikipedia.org/w/index.php?title=File:Cone-fundamentals-with-srgb-spectrum.svg  License: Public Domain  Contributors:BenRGFile:Spectrum locus 12.png  Source: http://en.wikipedia.org/w/index.php?title=File:Spectrum_locus_12.png  License: Public Domain  Contributors: KoenBFile:Eyesensitivity.png  Source: http://en.wikipedia.org/w/index.php?title=File:Eyesensitivity.png  License: Public Domain  Contributors: Original uploader was Skatebiker at en.wikipediaFile:Rainbow comparison.png  Source: http://en.wikipedia.org/w/index.php?title=File:Rainbow_comparison.png  License: Creative Commons Attribution-Sharealike 3.0  Contributors:User:zarnivopFile:Cie Chart with sRGB gamut by spigget.png  Source: http://en.wikipedia.org/w/index.php?title=File:Cie_Chart_with_sRGB_gamut_by_spigget.png  License: Creative CommonsAttribution-Sharealike 3.0  Contributors: SpiggetImage:Ventral-dorsal streams.svg  Source: http://en.wikipedia.org/w/index.php?title=File:Ventral-dorsal_streams.svg  License: Creative Commons Attribution-ShareAlike 3.0 Unported Contributors: Javier Carro, Lokal Profil, Selket, Was a beeImage:Eye Line of sight.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Eye_Line_of_sight.jpg  License: Public Domain  Contributors: Hans-Werner34, Saibo, 1 anonymous editsImage:Vision 2 secondes.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Vision_2_secondes.jpg  License: Creative Commons Attribution 3.0  Contributors: Hans-Werner Hunziker

License 115

LicenseCreative Commons Attribution-Share Alike 3.0 Unported//creativecommons.org/licenses/by-sa/3.0/