Digital Image Processing, 3rd ed.Digital Image Processing, 3rd ed.
www.ImageProcessingPlace.com
Gonzalez & Woods
Ch t 6Ch t 6Chapter 6Color Image Processing
Chapter 6Color Image Processing
1020
1018Ult i l t
10121014101610
Infrared
UltravioletVisible
106108101010
AM R diFM Radio + TVMicrowave
102104106 AM Radio
© 1992–2008 R. C. Gonzalez & R. E. Woods
Digital Image Processing, 3rd ed.Digital Image Processing, 3rd ed.
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Gonzalez & Woods
Ch t 6Ch t 6Chapter 6Color Image Processing
Chapter 6Color Image Processing
ColorimetricColorimetricColor Perception involve Hue, Saturation, and Lightness Hue :distinguish among colors such as red, green, and purple.g g , g , p pSaturation :refer to how color far from gray.Lightness: the perceived intensity of a reflecting object.Brightness :refer to the perceived intensity of self luminousBrightness :refer to the perceived intensity of self-luminous.
White “Pure”color
Artists TermsTint: results of adding white pigments
GraysShades
Tonesg p g
pure pigmentsShade: comes from adding black pigments
to pure pigments
© 1992–2008 R. C. Gonzalez & R. E. Woods
BlackTone:results of adding both black and white
pigments to pure pigments
Digital Image Processing, 3rd ed.Digital Image Processing, 3rd ed.
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Gonzalez & Woods
Ch t 6Ch t 6Chapter 6Color Image Processing
Chapter 6Color Image Processing
Color Models: GreenColor Models: The Newton Color Circle
CyanYellow
BlueRed
• The Newton color circle provides a convenient way to perceive
Magenta
p y pthe additive mixing properties of colors.
• The R,G,B and their complementary colors C,M,Y are placed on the circle in the order of the wavelengths of the corresponding
© 1992–2008 R. C. Gonzalez & R. E. Woods
the circle in the order of the wavelengths of the corresponding spectral colors.
Digital Image Processing, 3rd ed.Digital Image Processing, 3rd ed.
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Gonzalez & Woods
Ch t 6Ch t 6Chapter 6Color Image Processing
Chapter 6Color Image Processing
• The separation of colors by a prism expose a continuous range of spectral colors
© 1992–2008 R. C. Gonzalez & R. E. Woods
Digital Image Processing, 3rd ed.Digital Image Processing, 3rd ed.
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Gonzalez & Woods
Ch t 6Ch t 6Chapter 6Color Image Processing
Chapter 6Color Image Processing
• A spectral color is composed of a single wavelength p p g g• The helium-neon laser monochromatic light is red (632 nm). • Most colored objects give off a range of wavelengths and the
characterization of color is much more than the statement ofcharacterization of color is much more than the statement of wavelength.
© 1992–2008 R. C. Gonzalez & R. E. Woods
Digital Image Processing, 3rd ed.Digital Image Processing, 3rd ed.
www.ImageProcessingPlace.com
Gonzalez & Woods
Ch t 6Ch t 6Chapter 6Color Image Processing
Chapter 6Color Image Processing
© 1992–2008 R. C. Gonzalez & R. E. Woods
Digital Image Processing, 3rd ed.Digital Image Processing, 3rd ed.
www.ImageProcessingPlace.com
Gonzalez & Woods
Ch t 6Ch t 6Chapter 6Color Image Processing
Chapter 6Color Image Processing
Primary and Secondary colorsPrimary and Secondary colors
© 1992–2008 R. C. Gonzalez & R. E. Woods
Digital Image Processing, 3rd ed.Digital Image Processing, 3rd ed.
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Gonzalez & Woods
Ch t 6Ch t 6Chapter 6Color Image Processing
Chapter 6Color Image Processing
St d d C l M d lStandard Color ModelCommission Intenationale de l’Eclairage (CIE), 1931 defined three standard
i i ll d X YZ t l R d G Blprimaries, called X,Y,Z to replace Red, Green, Blue.
The primaries are used to match color by using three corresponding by us g t ee co espo d gcolor-matching functions
© 1992–2008 R. C. Gonzalez & R. E. Woods
Digital Image Processing, 3rd ed.Digital Image Processing, 3rd ed.
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Gonzalez & Woods
Ch t 6Ch t 6Chapter 6Color Image Processing
Chapter 6Color Image Processing
CIE Chromatic DiagramgChromatic values depend on dominant wavelength and saturation and independentof luminous energy.of luminous energy.Consider a color C, the we can Write C = XX + YY + ZZNormalize Against X+Y+Zgx = X/(X+Y+Z) y = Y/(X+Y+Z) z = Z/(X+Y+Z) We know that x+y+z = 1, and the luminanceinformation usually in Y (Y cef.), thus we can recover X,Y,Z X Y ( / ) Y Y Z Y(1 )/
The XYZ space
© 1992–2008 R. C. Gonzalez & R. E. Woods
X = Y (x/y) ; Y = Y ; Z = Y(1-x-y)/y Plotting these parameters
Digital Image Processing, 3rd ed.Digital Image Processing, 3rd ed.
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Gonzalez & Woods
Ch t 6Ch t 6XYZ Color Space
Chapter 6Color Image Processing
Chapter 6Color Image Processing
p
© 1992–2008 R. C. Gonzalez & R. E. Woods
Digital Image Processing, 3rd ed.Digital Image Processing, 3rd ed.
www.ImageProcessingPlace.com
Gonzalez & Woods
Ch t 6Ch t 6Chapter 6Color Image Processing
Chapter 6Color Image Processing
© 1992–2008 R. C. Gonzalez & R. E. Woods
Digital Image Processing, 3rd ed.Digital Image Processing, 3rd ed.
www.ImageProcessingPlace.com
Gonzalez & Woods
Ch t 6Ch t 6Chapter 6Color Image Processing
Chapter 6Color Image Processing
When two color A and B are addedW e wo co o a d a e addedtogether new color C lies on the lineconnects both colors.In the side Figure, B defines the dominantwavelength, and the ratio AC to BC expressedas a percent of the excitation purity of A.The closer A to C the more light A includes.
Complementary colors are those that can bemixed to produce white light. D and E on the side Figure are complementary colorsside Figure are complementary colors.Nonspectral color are those that can not be defined by dominant wavelength such as F.Color gamuts or color ranges is the effect of
© 1992–2008 R. C. Gonzalez & R. E. Woods
Color gamuts or color ranges is the effect of adding colors together
Digital Image Processing, 3rd ed.Digital Image Processing, 3rd ed.
www.ImageProcessingPlace.com
Gonzalez & Woods
Ch t 6Ch t 6Chapter 6Color Image Processing
Chapter 6Color Image Processing
© 1992–2008 R. C. Gonzalez & R. E. Woods
Digital Image Processing, 3rd ed.Digital Image Processing, 3rd ed.
www.ImageProcessingPlace.com
Gonzalez & Woods
Ch t 6Ch t 6Chapter 6Color Image Processing
Chapter 6Color Image Processing
© 1992–2008 R. C. Gonzalez & R. E. Woods
Digital Image Processing, 3rd ed.Digital Image Processing, 3rd ed.
www.ImageProcessingPlace.com
Gonzalez & Woods
Ch t 6Ch t 6Chapter 6Color Image Processing
Chapter 6Color Image Processing
RGB Color ModelThe color range (gamut) RGB model is defined by the CRT’s phosphor.
C = RR + GG + BB
Let us look at these colors in XYZ spaceLet us look at these colors in XYZ spaceRGB NTSC CIE MonitorR (0.67, 0.33) (0.73, 0.26) (0.62, 0.34)G (0.21, 0.71) (0.27, 0.71) (0 26 0 59)G (0.21, 0.71) (0.27, 0.71) (0.26, 0.59)B (0.14, 0.08) (0.16, 0.01) (0.15, 0.07)
© 1992–2008 R. C. Gonzalez & R. E. Woods
Digital Image Processing, 3rd ed.Digital Image Processing, 3rd ed.
www.ImageProcessingPlace.com
Gonzalez & Woods
Ch t 6Ch t 6Chapter 6Color Image Processing
Chapter 6Color Image Processing
© 1992–2008 R. C. Gonzalez & R. E. Woods
Digital Image Processing, 3rd ed.Digital Image Processing, 3rd ed.
www.ImageProcessingPlace.com
Gonzalez & Woods
Ch t 6Ch t 6Chapter 6Color Image Processing
Chapter 6Color Image Processing
© 1992–2008 R. C. Gonzalez & R. E. Woods
Digital Image Processing, 3rd ed.Digital Image Processing, 3rd ed.
www.ImageProcessingPlace.com
Gonzalez & Woods
Ch t 6Ch t 6CMY Color Model
Chapter 6Color Image Processing
Chapter 6Color Image Processing
Cyan magenta and blue are the complements of red green blueCyan, magenta, and blue are the complements of red, green, blue. CMY is important when dealing with hardcopy that deposit color pigments onto paper.
CM =
111
RGB
-
GR
MC
11
Y 1 B
C11
RG
MC
GR
BY
11
1
MY
= 11
GB
-
YM
BG
11
© 1992–2008 R. C. Gonzalez & R. E. Woods
Digital Image Processing, 3rd ed.Digital Image Processing, 3rd ed.
www.ImageProcessingPlace.com
Gonzalez & Woods
Ch t 6Ch t 6Chapter 6Color Image Processing
Chapter 6Color Image Processing
YIQ Color Model
YIQ is used by the US commercial TV.
Q• YIQ model exploits two properties of the visual system
– More sensitive to changes luminance than to change hue or saturationObj t th t t l ll t f fi ld f i d– Object that cover an extremely small part of our field of view, produce a limit color sensation.
• Y is the luminance (the same Y in XYZ space).h h i i i d d d d i d• The chromaticity is encoded encoded in I and Q
• Only Y component will show black/White TV• More bits are used for Y, and either I or Q has less bits than the other.
GR
IY
321027505960114.0587.0299.0
© 1992–2008 R. C. Gonzalez & R. E. Woods
B
GQI
311.0528.0212.0321.0275.0596.0
Digital Image Processing, 3rd ed.Digital Image Processing, 3rd ed.
www.ImageProcessingPlace.com
Gonzalez & Woods
Ch t 6Ch t 6Chapter 6Color Image Processing
Chapter 6Color Image Processing
HSI ModelHSI Model The relationship betweenRGB and HSI
RGB to HSIGB
H
]))(()[(2)()(cos
360
2/121
BGBRGRBRGR
GBH
3/)(
)],,[min()(
31
]))(()[(2
BGRI
BGRBGR
S
BGBRGR
© 1992–2008 R. C. Gonzalez & R. E. Woods
3/)( BGRI
Digital Image Processing, 3rd ed.Digital Image Processing, 3rd ed.
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Gonzalez & Woods
Ch t 6Ch t 6Chapter 6Color Image Processing
Chapter 6Color Image Processing
Hue and saturation in the HSI color model.• The angle from the red axis• The angle from the red axis
gives the hue• The length of the vector
i h iis the saturation.
© 1992–2008 R. C. Gonzalez & R. E. Woods
Digital Image Processing, 3rd ed.Digital Image Processing, 3rd ed.
www.ImageProcessingPlace.com
Gonzalez & Woods
Ch t 6Ch t 6Chapter 6Color Image Processing
Chapter 6Color Image Processing
HSI RGBHSI to RGB
)1()1200(
SIBHfor
)()60cos(
)cos(1
)(
HHSIR
)(3 BRIG
240360240120240120
HHHHHH
)cos(1
)1(240360240
HSIR
SIBHHH
© 1992–2008 R. C. Gonzalez & R. E. Woods
)(3)60cos(
1
BRIGH
IR
Digital Image Processing, 3rd ed.Digital Image Processing, 3rd ed.
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Gonzalez & Woods
Ch t 6Ch t 6Chapter 6Color Image Processing
Chapter 6Color Image Processing
© 1992–2008 R. C. Gonzalez & R. E. Woods
Digital Image Processing, 3rd ed.Digital Image Processing, 3rd ed.
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Gonzalez & Woods
Ch t 6Ch t 6Chapter 6Color Image Processing
Chapter 6Color Image Processing
In various color processing applications it is possible to use the corresponding Red, p g ,Green, and Blue channels
© 1992–2008 R. C. Gonzalez & R. E. Woods
Digital Image Processing, 3rd ed.Digital Image Processing, 3rd ed.
www.ImageProcessingPlace.com
Gonzalez & Woods
Ch t 6Ch t 6Chapter 6Color Image Processing
Chapter 6Color Image Processing
© 1992–2008 R. C. Gonzalez & R. E. Woods
Digital Image Processing, 3rd ed.Digital Image Processing, 3rd ed.
www.ImageProcessingPlace.com
Gonzalez & Woods
Ch t 6Ch t 6Chapter 6Color Image Processing
Chapter 6Color Image Processing
© 1992–2008 R. C. Gonzalez & R. E. Woods
Digital Image Processing, 3rd ed.Digital Image Processing, 3rd ed.
www.ImageProcessingPlace.com
Gonzalez & Woods
Ch t 6Ch t 6Chapter 6Color Image Processing
Chapter 6Color Image Processing
l di fColor Coding for visualization
© 1992–2008 R. C. Gonzalez & R. E. Woods
Digital Image Processing, 3rd ed.Digital Image Processing, 3rd ed.
www.ImageProcessingPlace.com
Gonzalez & Woods
Ch t 6Ch t 6Chapter 6Color Image Processing
Chapter 6Color Image Processing
© 1992–2008 R. C. Gonzalez & R. E. Woods
Digital Image Processing, 3rd ed.Digital Image Processing, 3rd ed.
www.ImageProcessingPlace.com
Gonzalez & Woods
Ch t 6Ch t 6Chapter 6Color Image Processing
Chapter 6Color Image Processing
Color Image ProcessingColor Image Processing
© 1992–2008 R. C. Gonzalez & R. E. Woods
Digital Image Processing, 3rd ed.Digital Image Processing, 3rd ed.
www.ImageProcessingPlace.com
Gonzalez & Woods
Ch t 6Ch t 6Chapter 6Color Image Processing
Chapter 6Color Image Processing
Color Transformation
© 1992–2008 R. C. Gonzalez & R. E. Woods
Digital Image Processing, 3rd ed.Digital Image Processing, 3rd ed.
www.ImageProcessingPlace.com
Gonzalez & Woods
Ch t 6Ch t 6Chapter 6Color Image Processing
Chapter 6Color Image Processing
© 1992–2008 R. C. Gonzalez & R. E. Woods
Digital Image Processing, 3rd ed.Digital Image Processing, 3rd ed.
www.ImageProcessingPlace.com
Gonzalez & Woods
Ch t 6Ch t 6Chapter 6Color Image Processing
Chapter 6Color Image Processing
© 1992–2008 R. C. Gonzalez & R. E. Woods
Digital Image Processing, 3rd ed.Digital Image Processing, 3rd ed.
www.ImageProcessingPlace.com
Gonzalez & Woods
Ch t 6Ch t 6Chapter 6Color Image Processing
Chapter 6Color Image Processing
© 1992–2008 R. C. Gonzalez & R. E. Woods
Digital Image Processing, 3rd ed.Digital Image Processing, 3rd ed.
www.ImageProcessingPlace.com
Gonzalez & Woods
Ch t 6Ch t 6Chapter 6Color Image Processing
Chapter 6Color Image Processing
© 1992–2008 R. C. Gonzalez & R. E. Woods
Digital Image Processing, 3rd ed.Digital Image Processing, 3rd ed.
www.ImageProcessingPlace.com
Gonzalez & Woods
Ch t 6Ch t 6Chapter 6Color Image Processing
Chapter 6Color Image Processing
© 1992–2008 R. C. Gonzalez & R. E. Woods
Digital Image Processing, 3rd ed.Digital Image Processing, 3rd ed.
www.ImageProcessingPlace.com
Gonzalez & Woods
Ch t 6Ch t 6Chapter 6Color Image Processing
Chapter 6Color Image Processing
© 1992–2008 R. C. Gonzalez & R. E. Woods
Digital Image Processing, 3rd ed.Digital Image Processing, 3rd ed.
www.ImageProcessingPlace.com
Gonzalez & Woods
Ch t 6Ch t 6Chapter 6Color Image Processing
Chapter 6Color Image Processing
© 1992–2008 R. C. Gonzalez & R. E. Woods
Digital Image Processing, 3rd ed.Digital Image Processing, 3rd ed.
www.ImageProcessingPlace.com
Gonzalez & Woods
Ch t 6Ch t 6Chapter 6Color Image Processing
Chapter 6Color Image Processing
© 1992–2008 R. C. Gonzalez & R. E. Woods
Digital Image Processing, 3rd ed.Digital Image Processing, 3rd ed.
www.ImageProcessingPlace.com
Gonzalez & Woods
Ch t 6Ch t 6Chapter 6Color Image Processing
Chapter 6Color Image Processing
© 1992–2008 R. C. Gonzalez & R. E. Woods
Digital Image Processing, 3rd ed.Digital Image Processing, 3rd ed.
www.ImageProcessingPlace.com
Gonzalez & Woods
Ch t 6Ch t 6Chapter 6Color Image Processing
Chapter 6Color Image Processing
© 1992–2008 R. C. Gonzalez & R. E. Woods
Digital Image Processing, 3rd ed.Digital Image Processing, 3rd ed.
www.ImageProcessingPlace.com
Gonzalez & Woods
Ch t 6Ch t 6Chapter 6Color Image Processing
Chapter 6Color Image Processing
© 1992–2008 R. C. Gonzalez & R. E. Woods
Digital Image Processing, 3rd ed.Digital Image Processing, 3rd ed.
www.ImageProcessingPlace.com
Gonzalez & Woods
Ch t 6Ch t 6Chapter 6Color Image Processing
Chapter 6Color Image Processing
© 1992–2008 R. C. Gonzalez & R. E. Woods
Digital Image Processing, 3rd ed.Digital Image Processing, 3rd ed.
www.ImageProcessingPlace.com
Gonzalez & Woods
Ch t 6Ch t 6Chapter 6Color Image Processing
Chapter 6Color Image Processing
© 1992–2008 R. C. Gonzalez & R. E. Woods
Digital Image Processing, 3rd ed.Digital Image Processing, 3rd ed.
www.ImageProcessingPlace.com
Gonzalez & Woods
Ch t 6Ch t 6Chapter 6Color Image Processing
Chapter 6Color Image Processing
© 1992–2008 R. C. Gonzalez & R. E. Woods
Digital Image Processing, 3rd ed.Digital Image Processing, 3rd ed.
www.ImageProcessingPlace.com
Gonzalez & Woods
Ch t 6Ch t 6Chapter 6Color Image Processing
Chapter 6Color Image Processing
© 1992–2008 R. C. Gonzalez & R. E. Woods
Digital Image Processing, 3rd ed.Digital Image Processing, 3rd ed.
www.ImageProcessingPlace.com
Gonzalez & Woods
Ch t 6Ch t 6Chapter 6Color Image Processing
Chapter 6Color Image Processing
© 1992–2008 R. C. Gonzalez & R. E. Woods
Digital Image Processing, 3rd ed.Digital Image Processing, 3rd ed.
www.ImageProcessingPlace.com
Gonzalez & Woods
Ch t 6Ch t 6Chapter 6Color Image Processing
Chapter 6Color Image Processing
© 1992–2008 R. C. Gonzalez & R. E. Woods
Digital Image Processing, 3rd ed.Digital Image Processing, 3rd ed.
www.ImageProcessingPlace.com
Gonzalez & Woods
Ch t 6Ch t 6Chapter 6Color Image Processing
Chapter 6Color Image Processing
© 1992–2008 R. C. Gonzalez & R. E. Woods
Digital Image Processing, 3rd ed.Digital Image Processing, 3rd ed.
www.ImageProcessingPlace.com
Gonzalez & Woods
Ch t 6Ch t 6Chapter 6Color Image Processing
Chapter 6Color Image Processing
© 1992–2008 R. C. Gonzalez & R. E. Woods
Digital Image Processing, 3rd ed.Digital Image Processing, 3rd ed.
www.ImageProcessingPlace.com
Gonzalez & Woods
Ch t 6Ch t 6Chapter 6Color Image Processing
Chapter 6Color Image Processing
© 1992–2008 R. C. Gonzalez & R. E. Woods
Digital Image Processing, 3rd ed.Digital Image Processing, 3rd ed.
www.ImageProcessingPlace.com
Gonzalez & Woods
Ch t 6Ch t 6Chapter 6Color Image Processing
Chapter 6Color Image Processing
© 1992–2008 R. C. Gonzalez & R. E. Woods