Color Appearance Models Second Edition

Mark D. Fairchild

Munsell Color Science Laboratoiy Rochester Institute of Technology, USA

John Wiley & Sons, Ltd Contents

Series Preface xiii Preface XV Introduction xix

1 Human Color Vision 1 1.1 Optics of the Eye 1 1.2 The Retina 6 1.3 Visual Signal Processing 12 1.4 Mechanisms of Color Vision 17 1.5 Spatial and Temporal Properties of Color Vision 26 1.6 Color Vision Deficiencies 30 1.7 Key Features for Color Appearance Modeling 34

2 Psychophysics 35 2.1 Psychophysics Defined 36 2.2 Historical Context 37 2.3 Hierarchy of Scales 40 2.4 Threshold Techniques 42 2.5 Matching Techniques 45 2.6 One-Dimensional Scaling 46 2.7 Multidimensional Scaling 49 2.8 Design of Psychophysical Experiments 50 2.9 Importance in Color Appearance Modeling 52

3 Colorimetry 53 3.1 Basic and Advanced Colorimetry 53 3.2 Whyis Color? 54 3.3 Light Sources and Illuminants 55 3.4 Colored Materials 59 3.5 The Human Visual Response 66 3.6 Tristimulus Values and Color Matching Functions 70 3.7 Chromaticity Diagrams 77 3.8 CIE Color Spaces 78 3.9 Color Difference Specification 80 3.10 The Next Step , 82 viii CONTENTS

4 Color Appearance Terminology 83 4.1 Importance of Definitions 83 4.2 Color 84 4.3 Hue 85 4.4 Brightness and Lightness 86 4.5 Colorfulness and Chroma 87 4.6 Saturation 88 4.7 Unrelated and Related Colors 88 4.8 Definitions in Equations 90 4.9 Brightness-Colorfulness vs Lightness-Chroma 91

5 Color Order Systems 94 5.1 Overvlew and Requirements 94 5.2 The Munsell Book of Color 96 5.3 The Swedish Natural Color System (NCS) 99 5.4 The Colorcurve System 102 5.5 Other Color Order Systems 103 5.6 Uses of Color Order Systems 106 5.7 Color Naming Systems 109

6 Color Appearance Phenomena 111 6.1 What Are Color Appearance Phenomena? 111 6.2 Simultaneous Contrast, Crispening, and Spreading 113 6.3 Bezold-Brücke Hue Shift (Hue Changes with Luminance) 116 6.4 Abney Effect (Hue Changes with Colorimetric Purity) 117 6.5 Helmholtz-Kohlrausch Effect (Brightness Depends on Luminance and Chromaticity) 119 6.6 Hunt Effect (Colorfulness Increases with Luminance) 120 6.7 Stevens Effect (Contrast Increases with Luminance) 122 6.8 Helson- Judd Effect (Hue of Nonselective Samples) 123 6.9 Bartleson-Breneman Equations (Image Contrast Changes with Surround) 125 6.10 Discounting the Illuminant 127 6.11 Other Context and Structural Effects 127 6.12 Color Constancy? 132

7 Viewing Conditions 134 7.1 Configuration of the Viewing Field 134 7.2 Colorimetric Specification of the Viewing Field 138 7.3 Modes of Viewing 141 7.4 Unrelated and Related Colors Revisited 144

8 Chromatic Adaptation 146 8.1 Light, Dark, and Chromatic Adaptation 147 8.2 Physiology 149 8.3 Sensory and Cognitive Mechanisms 157 CONTENTS •

8.4 Corresponding-colors Data 159 8.5 Models 162 8.6 Computational Color Constancy 164

9 Chromatic Adaptation Models 166 9.1 von Kries Model 168 9.2 RetinexTheory 171 9.3 Nayatani et al Model 172 9.4 Guth's Model 174 9.5 Fairchild's Model 177 9.6 Herding CATs 179 9.7 CAT02 181

10 Color Appearance Models 183 10.1 Definition of Color Appearance Models 183 10.2 Construction of Color Appearance Models 184 10.3 CIELAB 185 10.4 Why Not Use Just CIELAB? 193 10.5 What About CIELUV? 194

11 The Nayatani et al. Model 196 11.1 Objectives and Approach 196 11.2 InputData 197 11.3 Adaptation Model 198 11.4 Opponent Color Dimensions 200 11.5 Brightness 201 11.6 Lightness 202 11.7 Hue 202 11.8 Saturation 203 11.9 Chroma 203 11.10 Colorfulness 204 11.11 Inverse Model 204 11.12 Phenomena Predicted 205 11.13 Why Not Use Just the Nayatani et al. Model? 205

12 The Hunt Model 208 12.1 Obj ectives and Approach 208 12.2 Input Data 209 12.3 Adaptation Model 211 12.4 Opponent Color Dimensions 215 12.5 Hue 216 12.6 Saturation 217 12.7 Brightness 218 12.8 Lightness 220 12.9 Chroma 220 12.10 Colorfulness 220 CONTENTS

12.11 Inverse Model 221 12.12 Phenomena Predicted 222 12.13 Why Not Use Just the Hunt Model? 224

13 The RLAB Model 225 13.1 Objectives and Approach 225 13.2 Input Data 227 13.3 Adaptation Model 228 13.4 Opponent Color Dimensions 230 13.5 Lightness 232 13.6 Hue 232 13.7 Chroma 234 13.8 Saturation 234 13.9 Inverse Model 234 13.10 Phenomena Predicted 236 13.11 Why Not Use Just the RLAB Model? 236

14 Other Models 238 14.1 Overview 238 14.2 ATD Model 239 14.3 LLAB Model 245

15 The CIE Color Appearance Model (1997), CIECAM97s 252 15.1 Historical Development, Objectives, and Approach 252 15.2 Input Data 255 15.3 Adaptation Model 255 15.4 Appearance Correlates 257 15.5 Inverse Model 259 15.6 Phenomena Predicted 259 15.7 The ZLAB Color Appearance Model 260 15.8 Why Not Use Just CIECAM97s? 264

16 CIECAM02 265 16.1 Objectives and Approach 265 16.2 Input Data 266 16.3 Adaptation Model 267 16.4 Opponent Color Dimensions 271 16.5 Hue 271 16.6 Lightness 272 16.7 Brightness 272 16.8 Chroma 273 16.9 Colorfulness 273 16.10 Saturation 273 16.11 Cartesian Coordinates 273 16.12 Inverse Model 274 16.13 Implementation Guidelines 274 CONTENTS

16.14 Phenomena Predicted 275 16.15 Why Not Use Just CIECAM02? 275 16.16 Outlook 277

17 Testing Color Appearance Models 278 17.1 Overview 278 17.2 Qualitative Tests 279 17.3 Corresponding Colors Data 283 17.4 Magnitude Estimation Experiments 285 17.5 Direct Model Tests 287 17.6 CIEActMties 291 17.7 A Pictorial Review of Color Appearance Models 295

18 Traditional Colorimetric Applications 299 18.1 Color Rendering 299 18.2 Color Differences 301 18.3 Indices of Metamerism 304 18.4 A General System of Colorimetry? 306

19 Device-independent Color Imaging 308 19.1 The Problem 309 19.2 Levels of Color Reproduction 310 19.3 A Revised Set of Objectives 312 19.4 General Solution 315 19.5 Device Calibration and Characterization 316 19.6 The Need for Color Appearance Models 321 19.7 Definition ofViewing Conditions 321 19.8 Viewing-conditions-independent Color Space 323 19.9 Gamut Mapping 324 19.10 Color Preferences 327 19.11 Inverse Process 328 19.12 Example System 328 19.13 ICC Implementation 330

20 Image Appearance Modeling and The Future 334 20.1 From Color Appearance to Image Appearance 335 20.2 The iCAM Framework 340 20.3 A Modular Image-difference Model 346 2Q.4 Image Appearance and Rendering Applications 350 20.5 Image Difference and Quality Applications 355 20.6 Future Directions 357

References 361 Index 378