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Why Java ? Java is rich in it’s support of imaging and color. Demonstrations can (easily) be shared on the web Inherent portability to different platforms and hardware.
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Use of Java for Demonstration Use of Java for Demonstration of Color Science Concepts of Color Science Concepts
Presentation of an MS Project, submitted to The Faculty of the Computer Science Department, in
partial fulfillment of the requirements for the degree of Master of Science in Computer
Science from Rochester Institute of Technology
John A. MooreApril 29, 1998
Project ObjectivesProject Objectives
• Gain knowledge and experience with Java Programming.
• Apply my knowledge of Color Science.• Generate a Package of general purpose
Color Science Java classes for others to use and grow.
• Complete requirements for MS Degree.
Why Java ?Why Java ?
• Java is rich in it’s support of imaging and color.
• Demonstrations can (easily) be shared on the web
• Inherent portability to different platforms and hardware.
Development EnvironmentDevelopment Environment
• Experimented with many…– Microsoft Visual J++– Semantics Visual Café for Java– Basic JDK
• Settled on JpadPro– Basic project management– Support for custom Packages– Colored coded text editor– Easy to use and learn
JpadPro JpadPro http://www.modelworks.comhttp://www.modelworks.com
Color Science FundamentalsColor Science Fundamentals
Additive Color Mixing Subtractive Color Mixing
The Java DemonstrationsThe Java Demonstrations
Three Color Science Demonstrations
Simple Subtractive Color MixingSimple Additive Color Mixing
Calculation of Helmholtz coordinates
Simple Subtractive Color Simple Subtractive Color MixingMixing
Features & Functions• Double Buffered imaging to avoid
flicker• Back-light switch to emphasize
subtraction of light.• System requirements check.• Instruction panel
Show Subtractive Show Subtractive Color Mixing AppletColor Mixing Applet
Additive Color MixingAdditive Color Mixing
Features & Functions• Allows user to choose color of each
primary• Select a color ‘mixture’ from a color
picker• Allows the user to see the selected
color in a mixer panel.• Utilizes a ‘super cell’ technique
Primary ComponentsPrimary Components
p1 p2 p3
p3 p1 p2
p2 p3 p1
p1 = primary 1p2 = primary 2p3 = primary 3
Monitor Pixel
Super pixel
Super Pixel ConceptSuper Pixel Concept
• Allows full RGB control over each “Primary”• More pleasing at 45 degree angle
Illustration of intensity variation for P1 only
P1
Where:RadialMax = ( Width / 2 ) / Tan 30RadialCenter = (Width / 2 ) / Cos 30
RadialCenter
RadialMax
30P1 P2
P3
Width
Color Picker Space Color Picker Space ImplementationImplementation
Show Additive mixing Show Additive mixing demonstrationdemonstration
coloRama
AdditiveMixerPanel
Primary
GamutPanel
PrimaryDisplay
colorPickerPanelShowMixPanel
ThreeSliderControl
gammutScreen
Class HierarchyClass Hierarchyfor Additive Color Mixingfor Additive Color Mixing
Three things to perceive colorThree things to perceive color
Source
Object
Eye
But how do you specify color….But how do you specify color….
237
224
103
Color Matching ExperimentsColor Matching Experiments
r, g, b Color Matching Functionr, g, b Color Matching Function
Wavelength ()
Transformed to x, y, zTransformed to x, y, z
• To avoid negative numbers and simplify calculations
• set y to equal the spectral luminous efficiency fnct (corresponding to a color’s lightness)
CIE 1931 Standard observer
Three things to perceive colorThree things to perceive color
ObjectSource Eye
300 400 500 600 700
300 400 500 600 700
Calculation of Tristimulus Calculation of Tristimulus ValuesValues
X = k PRxY = k PRyZ = k PRz
Where: k = 100Py
And P = relative power distribution of CIE standard illuminant R = spectral reflectance of the object
Chromaticity CoordinatesChromaticity Coordinates
• Translate the X, Y, Z to two dimensions for convenience
x = XX+Y+Z
y = YX+Y+Z
z = ZX+Y+Z
• Only need two points since: x + y + z = 1.0
Chromaticity DiagramChromaticity Diagram
The Helmholtz DemonstrationThe Helmholtz Demonstration
• Helmholtz coordinates are an alternative way to expressing chromaticity values.
But what are they…...
00
0.8
0.60.40.2
0.2
0.4
0.6
x
y
Select a White Point
Calculation of Helmholtz coordinatesCalculation of Helmholtz coordinates
Select a Sample Point
00
0.8
0.60.40.2
0.2
0.4
0.6
x
y
Calculation of Helmholtz coordinatesCalculation of Helmholtz coordinates
Next…Draw a
Line through
theWhite pointand
samplepoint
00
0.8
0.60.40.2
0.2
0.4
0.6
x
y
Calculation of Helmholtz coordinatesCalculation of Helmholtz coordinates
The “Dominant Wavelength”is determined
by the intersection
with the spectrum Locus.
00
0.8
0.60.40.2
0.2
0.4
0.6
x
y
Calculation of Helmholtz coordinatesCalculation of Helmholtz coordinates
...and the “excitation Purity” is
determined by the ratio of the
distances as shown.
00
0.8
0.60.40.2
0.2
0.4
0.6
x
y
Calculation of Helmholtz coordinatesCalculation of Helmholtz coordinates
AB
such thatPe = A/B
Complimentary WavelengthComplimentary Wavelength
The condition shown in yellow is met when...• The slope of the line is positive.• The y-value of the line at x is less than the y-value of the
locus at x.• The sample point x-chroma value is greater than the
White Point x-chroma value OR Sample point is a Complimentary Color...
The condition shown in green is met when…• The slope of the line is positive.• The y-value of the line at x is greater than the y-value of
the locus at x.• Sample point x-chroma value is less than the White Point
x-chroma value AND The sample point is not a Complimentary Color.
The condition shown in blue is met when...
• The slope of the line is negative.• The y-value of the line at x is greater than the y-value of
the locus at x.• Sample point x-chroma value is less than the White Point
x-chroma value OR The Sample point is a Complimentary Color...
The condition shown in pale red is met when...• The slope of the line is negative.• The y-value of the line at x is less than the y-value of the
locus at x.• Sample point x-chroma value is greater than the White
Point x-chroma value AND The Sample point is not a Complimentary Color...
AlgorithmAlgorithm
Show Show Helmholtz ApplicationHelmholtz Application
Helmholtz
helmholtzPanelchromaticityControls
illuminantPanel
colorSamplePanel
ChromaValuesPanel feedBackPanel
ChromaValuesPanel
feedBackPanel
chromaticityPanel
whitePointDataClass
Class HierarchyClass Hierarchyfor Additive Color Mixingfor Additive Color Mixing
Color_kit PackageColor_kit Packagecolor_kit.color_space
color_kit.color_space.uv_chromaticity color_kit.color_space.xy_10degree_chromaticity color_kit.color_space.xy_chromaticity
color_kit.dialogs color_kit.panels
color_kit.panels.bundles color_kit.panels.controls color_kit.panels.displays
color_kit.toolkit
Discussion of ResultsDiscussion of Results
• Numerous Java VM inconsistencies–Sun JDK, MS SDK, Netscape (Semantics)
• Wide performance variations• Java 1.1.5 VM roll-out
ConclusionConclusion
• Future Work• Acknowledgements
