Gamut mapping algorithms, implemented by color management systems, are an integral part of the color reproduction process. By adjusting the colors with appropriate algorithms, gamut mapping enables original colors to ‘fit’ inside differently shaped color gamuts and authentically transfers images across a range of media. This book illustrates the range of possible gamut mapping strategies for cross-media color reproduction, evaluates the performance of various options and advises on designing new, improved solutions. Starting with overviews of color science, reproduction and management, the text includes:
- a detailed survey of 90+ gamut mapping algorithms covering color-by-color reduction and expansion, spatial reduction, spectral reduction and gamut mapping for niche applications;
- a step-by-step example of a color’s journey from original to reproduction, via a digital workflow;
- a detailed analysis of color gamut computation, including a comparison of alternative techniques and an illustration of the gamuts of salient color sets and media;
- a presentation of both measurement-based and psychovisual evaluation of individual color reproductions;
- an overview of alternative approaches to gamut mapping proposed by the ISO and the CIE including an analysis of the building blocks of gamut mapping algorithms and the factors affecting their performance.
Color Gamut Mapping is a comprehensive resource for practicing color and imaging engineers, scientists and researchers working in the development of imaging devices, software and solutions. It is also a valuable reference for students of color and imaging science, as well as photographers, graphic designers and artists.
Table of Contents:
Foreword ix
Series Preface xi
Preface xiii
1. Introduction 1
1.1 What is Color Gamut Mapping? 1
1.2 Historical Context of Gamut Mapping 5
1.3 Who is this Book for? 7
1.4 What is in the Rest of the Book? 8
2. Basics of Color Science 11
2.1 What is Color? 11
2.2 Describing Color Experiences 12
2.3 The Color Ecosystem 16
2.4 The Human Visual System 17
2.5 Physical Color-related Properties 21
2.6 Colorimetry 25
2.7 Color Ecosystem Interactions 29
2.8 Digital Color Capture and Generation 35
2.9 Color Management 39
2.10 What can Affect the Appearance of a Pair of Stimuli? 41
2.11 Summary 42
3. Desired Color Reproduction Properties and their Evaluation 45
3.1 Color Reproduction Framework 45
3.2 Desired Color Reproduction Properties 47
3.3 Evaluating Reproductions 53
3.4 Case Study: Evaluating Printed Reproductions of a Displayed Image 70
3.5 Summary 71
4. Color Reproduction Data Flows 73
4.1 Device Color Spaces 73
4.2 Conceptual Stages of Color Reproduction 76
4.3 Closed-loop Color Management 81
4.4 sRGB Color Management 83
4.5 ICC Color Management 85
4.6 Windows Color System Color Management 88
4.7 Importance of Gamut Mapping in Color Reproduction 89
4.8 Summary 90
5. Overview of Gamut Mapping 91
5.1 Definitions 91
5.2 Aims of Gamut Mapping 94
5.3 Gamut Mapping Algorithm Context 95
5.4 Types of Gamut Mapping 96
5.5 Building Blocks of Gamut Mapping Algorithms 97
5.6 Factors Affecting Gamut Mapping 105
5.7 Will Gamut Mapping become Redundant? 107
6. Color Spaces for Gamut Mapping 111
6.1 Implications of Mapping Appearance Predictors 112
6.2 Which Appearance Attributes' Predictors to Map 114
6.3 Overview of Color Appearance Spaces 115
6.4 Mapping in Nonappearance Spaces 119
6.5 Choosing a Space for Gamut Mapping 121
7. Basic Computational Geometry for Gamut Mapping 123
7.1 Spaces, Points, Lines and Planes 123
7.2 Intersections 126
7.3 Is a Point Inside or Not? 128
7.4 Normals 129
7.5 Triangulation 131
7.6 Summary 132
8. Color Gamuts and their Computation 133
8.1 Challenges and Implications of Definition 134
8.2 Gamut Boundary Descriptor Algorithms 143
8.3 Evaluating and Operating on Gamut Boundary Descriptors 155
8.4 Examples of Salient Color Gamuts 160
8.5 Image Gamuts 167
8.6 Summary 169
9. A Case Study: Minimum Color Difference Gamut Clipping 171
9.1 The Original 171
9.2 The Destination Gamut 175
9.3 Minimum Color Difference Gamut Mapping 176
9.4 The Destination Image 182
9.5 Effect of Alternatives 183
9.6 Summary 191
10. Survey of Gamut Mapping Algorithms 193
10.1 Color-by-color Reduction 194
10.2 Color-by-color Expansion 220
10.3 Spatial Gamut Reduction 224
10.4 Spectral Gamut Mapping 234
10.5 Gamut Mapping for Special Applications 237
10.6 Summary 239
11. Gamut Mapping Algorithms and Color Management Systems 241
11.1 Gamut Mapping Algorithms for Closed-loop Color Management 241
11.2 Gamut Mapping Algorithms for sRGB Color Management 242
11.3 Gamut Mapping Algorithms for ICC Color Management 242
11.4 Gamut Mapping Algorithms for WCS Color Management 244
11.5 Types of Color Management Context 245
11.6 Spatial and Spectral Gamut Mapping 246
11.7 Conclusions 246
12. Evaluating Gamut Mapping Algorithms 247
12.1 Why is there no Reference Data Set in Gamut Mapping Algorithm Evaluation? 248
12.2 Characteristics of Published Gamut Mapping Algorithm Evaluation 250
12.3 What can be Said on the Basis of Existing Evaluation Results? 252
12.4 CIE Guidelines 253
12.5 Studying Specific Properties of Gamut Mapping Algorithms 255
12.6 Summary 258
13. Conclusions 261
References 265
Index 281
About the Author :
Dr Ján Morovi , Hewlett-Packard Espanola, S. L, Avda. Grealls, Barcelona, Spain
Ján Morovi is currently a Senior Color Scientist at Hewlett-Packard Espanola, Barcelona, Spain. He is highly regarded in the field of colour science, being Chair of the CIE (International Commission on Illumination) technical committee 8-03 on gamut mapping, a post he has held since 1998. Before his appointment in industry for Hewlett-Packard, Dr Morovi has also had academic experience at the University of Derby, UK. He has delivered lectures to an international audience, both academic and industrial, led industrially funded projects, and developed new commercial technologies. In addition, he has authored 62 academic publications, including book chapters, journal, and conference papers on colour gamut mapping, and also helped to create a CIE technical report detailing guidelines for the Evaluation of Mapping Algorithms.
Review :
“Jan Morovic does a good job of describing the many aspects of color. The first four chapters are expansive. They present summaries of the definition of color, basic color science, categories of possible color reproduction goals, and color mapping goals.” (COLOR research and application, June 2009)
