Why do we see what we see Color The property possessed by an object of producing different sensations on the eye as a result of the way the object reflects or transmits light Light transmission ID: 1018663
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1. Color TheoryWhat is color?Why do we see what we see?
2. ColorThe property possessed by an object of producing different sensations on the eye as a result of the way the object reflects or transmits light.
3. Lighttransmissionabsorptionreflectionlight sourceobserver
4. LightVisible region of the electromagnetic spectrum (380 to 780 nm).
5. Color AttributesHue (“Color”)Chromaticity (Saturation, Purity)Value (Lightness/Darkness)
6. Color MixingLight Additive mixingPrimaries: red, blue, greenBlack: absence of colorWhite: equal mixture of primary colorsDyes/PigmentsSubtractive mixingPrimaries: red, blue, yellowBlack: mixture of colorsWhite: absence of color
7. LightLight SourceLight SourceStandard Illuminant
8. 400500600700D65Daylight
9. 400500600700AIncandescent
10. 400500600700F2Fluorescent
11. Perceived ColorSPD of light source(s)Reflectance characteristics of specimenReflectance of surroundingsObserver (color vision, age, fatigue, training, etc.) Incidence angleViewing angle
12. Comparing ColorMore complications!SubstrateSizeOrientationProximityMetamerismOther visual effects
13. Illuminant MetamerismColors match under one light source, but not another. Different colorants have different reflectance propertiesSome light sources minimize the differences, others magnify them.CWFDaylight
14. Color InconstancyColor of ONE object varies under different light sources.Warm white fluorescentCool white fluorescentDaylightTungsten
15. Simultaneous Contrast
16. Munsell Color SystemDeveloped as a tool for art studentsIllustrates dimensions of hue, lightness, and chroma.No coordinates for color space mapping.
17. CIE Color System“Standard Observer” developed in 1931Observers matched a light at the bottom field with three colors of lights (Red, Green and Blue) in the top fieldSpectral curves into tristimulus values (X, Y and Z)Y correlates with lightness (X and Z do not correlate with hue or chroma)
18. CIE Chromaticity Diagram
19. More Chromaticity DiagramsCIEXYZ (1931, 1964)CIELUV (1960)CIE u’,v’ (1976)
20. 1976 CIELAB Color SpaceL* = lightness/darknessBlack: L* = 0White: L* = 100a* = red/greenRed: +a*Green: -a*b* = yellow/blueYellow: +b*Blue: -b*
21. CIELAB Color DifferenceThe relative sizes of differences between colors plotted in various parts of CIE color space do not correspond well to the size of the differences seen by the eye. ΔE* = [(ΔL*)² + (Δa*)² + (Δb*)²]½
22. CMC Tolerance SystemCMC (l:c)AATCC TM173Color tolerances as ellipsoids.Ellipsoids are not consistent in size and shape throughout color space.
23. Color Difference EquationsΔE* = [(ΔL*)² + (Δa*)² + (Δb*)²]½
24. AATCC RA36 Color Measurement Test Methods Scope:To develop test methods relating to color science, to advise other AATCC committees involved with special problems on color,and to provide liaison between AATCC and other groups directly concerned with problems in color science.
25. ResourcesBerns, Roy S., Billmeyer and Saltzman’s Principles of Color Technology 3rd Edition, John Wiley & Sons Inc., 2000.Kuehni, Rolf G., Color Vision and Technology, AATCC, 2008.Aspland, Richard & Ann Laidlaw, AATCC Color Guidebook, AATCC, 2011