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COLOR CATEGORIES IN VARIOUS COLOR SPACES

The 9th CIC (Nov. 8, 2001) Scottsdale, AZ. COLOR CATEGORIES IN VARIOUS COLOR SPACES. Hirohisa Yaguchi Dept. of Information and Image Sciences Chiba University. CONTENTS. Importance of color name Review of development of color spaces Experiment on categorical color naming

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COLOR CATEGORIES IN VARIOUS COLOR SPACES

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  1. The 9th CIC (Nov. 8, 2001) Scottsdale, AZ COLOR CATEGORIES IN VARIOUS COLOR SPACES Hirohisa Yaguchi Dept. of Information and Image Sciences Chiba University

  2. CONTENTS • Importance of color name • Review of development of color spaces • Experiment on categorical color naming • Application; Categorical color rendering index

  3. Importance of Color Name • To communicate color information in every day life. • To categorize objects and recognize them. • Color names do not depend on viewing condition.

  4. Berlin and Kay’s basic color

  5. Eleven basic color names in OSA color space(Boynton and Olson, 1987)

  6. What Color Space Should We Map Color Name? • Object color space; OSA, Munsell System • Color stimulus space; XYZ • Nonlinear scale + complete chromatic adaptation space, CIELAB • Viewing condition independent color space: NCS,CIECAM97s

  7. Human color vision and advance of colorimetry

  8. Basic colorimetric system • LMS (Physiological system) • RGB (Physical system) • XYZ (Mathematical system)

  9. LMS (Physiological colorimetry)

  10. RGB (Physical colorimetry)

  11. XYZ (Mathematical colorimetry)

  12. CIELAB(CIE1976L*a*b*) • Color adaptation • White is always white • Non-linearity • Physical unit to psychological unit • Color opponency • Luminance and chromaticness

  13. CIELAB color space

  14. History of Color Appearance Models CIECAM97s CIE CIECAM97c Bradford-Hunt96S Hunt Hunt91 Hunt94 Bradford-Hunt96C Fairchild RLAB93 RLAB96 ZLAB Nayatani94 (CIE109-1994) Nayatani Nayatani97 Luo LLAB96 LLAB96b 1998 1996 1997 1991 1994 Others CIELAB（uniform color space ,CIE 1976) CIELUV (uniform color space ,CIE 1976) von Kries(chromatic adaptation transform , von Kries1902) ATD (color perception and visual adaptation , Guth 1995)

  15. CIE Color Appearance Model(CIECAM97s)

  16. CIECAM97s Color Space

  17. What Color Space Should We Map Color Name? • Object color space; Munsell System • Color stimulus space; XYZ • Nonlinear scale + complete chromatic adaptation color space, CIELAB • Viewing condition independent color space: CIECAM97s

  18. EXPERIMENT

  19. Light Sources

  20. Spectral Power Distributions of Light Sources (1)

  21. IL NX NH MHL H HF Spectral Power Distributions of Light Sources (2)

  22. Color Samples Named Basic Color in the Munsell Color System (1)

  23. Color Samples Named Basic Color in the Munsell Color System (2)

  24. Color Samples Named Basic Color in the Munsell Color System (3)

  25. Results in the Munsell Hue Circle

  26. Color samples consistently sorted into the same category of color name for typical three illuminants: D65, IL and H

  27. Color name regions in the CIE 1931(x, y) diagram (D65, IL, H)

  28. Color name regions in the CIE 1976 (a*, b*) plane (D65, IL, H)

  29. Color name regions in the CIECAM97s hue circle (D65, IL, H)

  30. Color name region determined by the OR-region for all illuminants

  31. Color name regions in the CIECAM97s hue circle (All illuminants)

  32. White, Gray and Black in the (C, J) Plane

  33. Red and Pink in the (C, J) Plane

  34. Orange and Brown in the (C, J) Plane

  35. Blue and Green in the (h,J) Plane

  36. Hmin Cmax Cmin Hmax Specification of color name regions in the CIECAM97s space

  37. Color name regions in the CIECAM97s space 75<J 55<J<75 35<J<55 J<35

  38. Application of Color Name Map • Color name reproduction in imaging technology • Gamut mapping keeping color name constant • Color rendering index of light sources based on categorical color rather than color difference

  39. 5R 5R 5P 5Y 5Y 5P 0 2 4 6 8 10 12 14 0 2 4 6 8 10 12 14 5B 5G 5B 5G Cool white fluorescent (W) High pressure mercury (H) Color Chips under Different Illuminant

  40. Boundary of color samples under the test light source “St” How to calculate ●CCRI for each test sample ● Averaged CCRI Boundary of Color name “Si” Hmax × × × × Cmin Cmax × × Hue angle × × Hmin Boundary of color samples under D65 Chroma Categorical color rendering index (CCRI)

  41. Relation between CCRI and Ra

  42. Conclusions • Eleven basic color name regions are clearly separated in the CIECAM97s color space • The CIECAM97s provides a good prediction of basic color name under various light sources • Color name map in CIECAM97s can be applied to many fields including imaging technology

  43. THANK YOU

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