COLOR CATEGORIES IN VARIOUS COLOR SPACES

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COLOR CATEGORIES IN VARIOUS COLOR SPACES
The 9th CIC (Nov. 8, 2001) Scottsdale, AZ

• Hirohisa Yaguchi
• Dept. of Information and Image Sciences
• Chiba University

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CONTENTS

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

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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.

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Berlin and Kays basic color
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Eleven basic color names in OSA color space
(Boynton and Olson, 1987)
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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

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Human color vision and advance of colorimetry
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Basic colorimetric system

• LMS (Physiological system)
• RGB (Physical system)
• XYZ (Mathematical system)

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LMS (Physiological colorimetry)
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RGB (Physical colorimetry)
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XYZ (Mathematical colorimetry)
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CIELAB(CIE1976Lab)

• Color adaptation
• White is always white
• Non-linearity
• Physical unit to psychological unit
• Color opponency
• Luminance and chromaticness

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CIELAB color space
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History of Color Appearance Models
CIECAM97s
CIE
CIECAM97c
Bradford-Hunt96S
Hunt
Hunt94
Hunt91
Bradford-Hunt96C
RLAB96
RLAB93
Fairchild
ZLAB
Nayatani94 (CIE109-1994)
Nayatani97
Nayatani

Luo
LLAB96b
LLAB96
1998
1996
1997
1994
1991
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)
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CIE Color Appearance Model(CIECAM97s)
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CIECAM97s Color Space
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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

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EXPERIMENT
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Light Sources
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Spectral Power Distributions of Light Sources (1)
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Spectral Power Distributions of Light Sources (2)
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Color Samples Named Basic Color in the Munsell
Color System (1)
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Color Samples Named Basic Color in the Munsell
Color System (2)
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Color Samples Named Basic Color in the Munsell
Color System (3)
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Results in the Munsell Hue Circle
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Color samples consistently sorted into the same
category of color name for typical three
illuminants D65, IL and H
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Color name regions in the CIE 1931(x, y) diagram
(D65, IL, H)
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Color name regions in the CIE 1976 (a, b) plane
(D65, IL, H)
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Color name regions in the CIECAM97s hue circle
(D65, IL, H)
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Color name region determined by the OR-region for
all illuminants
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Color name regions in the CIECAM97s hue circle
(All illuminants)
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White, Gray and Black in the (C, J) Plane
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Red and Pink in the (C, J) Plane
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Orange and Brown in the (C, J) Plane
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Blue and Green in the (h,J) Plane
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Specification of color name regions in the
CIECAM97s space
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Color name regions in the CIECAM97s space
75ltJ
55ltJlt75
35ltJlt55
Jlt35
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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

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Color Chips under Different Illuminant
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Categorical color rendering index (CCRI)
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Relation between CCRI and Ra
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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

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THANK YOU