Colorimetry Fundamentals and Applications

About the Authors ix

Series Preface xi

Preface xiii

Introduction xv

1 Light, Vision and Photometry 1

1.1 Light 1

1.2 Mechanism of the Human Eye 4

1.3 Adaptation and Responsivity of the Human Eye 7

1.4 Spectral Responsivity and the Standard Photometric Observer 9

1.5 Definition of Photometric Quantities 17

1.6 Photometric Units 21

1.7 Calculation and Measurement of Photometric Quantities 26

1.8 Relations Between Photometric Quantities 31

Note 1.1 Luminous Exitance, Illuminance, and Luminance of a Perfect Diffusing Plane Light Source 34

Note 1.2 Luminance and Brightness 36

2 Color Vision and Color Specification Systems 39

2.1 Mechanism of Color Vision 39

2.2 Chemistry of Color Vision 46

2.3 Color Specification and Terminology 48

2.4 Munsell Color System 52

2.5 Color System Using Additive Color Mixing 57

Note 2.1 Colorfulness, Chroma and Saturation 61

3 CIE Standard Colorimetric System 63

3.1 RGB Color Specification System 63

3.2 Conversion into XYZ Color Specification System 68

3.3 X₁₀Y₁₀Z₁₀ Color Specification System 71

3.4 Tristimulus Values and Chromaticity Coordinates 74

3.5 Metamerism 76

3.6 Dominant Wavelength and Purity 78

3.7 Color Temperature and Correlated Color Temperature 82

3.8 Illuminants and Light Sources 85

3.9 Standard and Supplementary Illuminants 92

Note 3.1 Derivation of Color Matching Functions from Guild and Wright's Results 96

Note 3.2 Conversion between Color Specification Systems 99

Note 3.3 Conversion into XYZ Color Specification System 101

Note 3.4 Imaginary Colors [X] and [Z] 105

Note 3.5 Photometric Quantities in the X 10 Y 10 Z 10 Color System 108

Note 3.6 Origin of the Term 'Metamerism' 109

Note 3.7 Simple Methods for Obtaining Correlated Color Temperature 110

Note 3.8 Color Temperature Conversion Filter 111

Note 3.9 Spectral Distribution of Black-body Radiation 113

4 Uniform Color Spaces 115

4.1 Uniform Chromaticity Diagrams 115

4.2 Uniform Lightness Scales (ULS) 122

4.3 CIE Uniform Color Spaces 127

4.4 Correlates of Perceived Attributes 132

4.5 Comparing CIELAB and CIELUV Color Spaces 134

4.6 Conversion of Color Difference 140

4.7 Color Difference Equations Based on CIELAB 143

Note 4.1 Calculation of Munsell Value V from Luminous Reflectance Y 144

Note 4.2 Modified CIELAB and CIELUV Equations for Dark Colors 146

Note 4.3 Other Color Difference Formulas 147

Note 4.4 Direct Calculation of Hue Difference DeltaH* 150

5 Measurement and Calculation of Colorimetric Values 153

5.1 Direct Measurement of Tristimulus Values 153

5.2 Spectral Colorimetry 156

5.3 Geometrical Conditions for Measurement 158

5.4 Calculation of Colorimetric Values 161

5.5 Colorimetric Values in CIELAB and CIELUV Uniform Color Spaces 167

Note 5.1 Spectral Colorimetry of Fluorescent Materials 172

Note 5.2 Reference Standard for Reflection Measurements 173

6 Evolution of CIE Standard Colorimetric System 175

6.1 Additive Mixing 176

6.2 Subtractive Mixing 180

6.3 Maximum Value of Luminous Efficacy and Optimal Colors 184

6.4 Chromatic Adaptation Process 188

6.5 von Kries' Predictive Equation for Chromatic Adaptation 191

6.6 CIE Predictive Equations for Chromatic Adaptation 194

6.7 Color Vision Models 197

6.8 Color Appearance Models 198

6.9 Analysis of Metamerism 204

Note 6.1 Color Mixing Rule 211

Note 6.2 Lambert-Beer Law 213

Note 6.3 Method for Calculating the Maximum Value of the Luminous Efficacy of Radiation 214<