Colorimetry

Janos Schanda, PhD, is Professor Emeritus of the University of Pannonia in Hungary, where he taught colorimetry and visual ergonomics. He headed the Department of Image Processing and Neurocomputing between 1996 and 2000, and served as secretary of the CIE. He is a member of the advisory boards of Color Research and Application, Lighting Research and Technology, Light and Engineering, and Journal of Light and Visual Environment.

Preface xvii

Contributors and Referees xxi

Part I Historic retrospection

1 Translation of CIE 1931 Resolutions on Colorimetry 1
Translated by P. Bodrogi

Decision 1 1

Decision 2 4

Appendix to Decision 2 5

Decision 3 5

Decision 3a 8

Decision 4 8

Decision 5 8

2 Professor Wright’s Paper from the Golden Jubilee Book: The Historical and Experimental Background to the 1931 CIE System of Colorimetry 9
W. D. Wright

Color mixture and measurement in the Nineteenth Century 9

American contributions to photometry and colorimetry, 1900–24 11

The run-up to the 1931 observer: 1924–30 12

The drama of 1931 17

Postscript to 1931 21

Note added in proof 22

References 22

Part II Colorimetric Fundamentals

3 CIE Colorimetry 25
János Schanda

Introduction 25

CIE standard colorimetric observers 27

The CIE 1931 standard colorimetric observer 29

Determination of the r( λ), g(λ), b( λ) color-matching functions 29

Derivation of the CIE XYZ trichromatic system from the CIE RGB trichromatic system 29

Tristimulus values and chromaticity coordinates 31

CIE 1964 standard colorimetric observer 35

k10 in the tristimulus values of self-luminous objects for the 10 observer 36

k10 in the tristimulus values of non-self-luminous objects for the 10 observer 36

Chromaticity coordinates for the 10 observer 37

Notes on the use of the CIE 1964 standard colorimetric observer 37

CIE illuminants and sources 37

CIE standard illuminant A and Planckian radiators 38

Daylight illuminants 40

CIE standard illuminant D 65 42

CIE illuminants 43

CIE sources and simulators for colorimetry 44

Source A 44

Sources B and c 45

Source D 65 45

Standards and recommendations for measuring reflecting/transmitting materials 47

Terms used in conjunction with transmission and reflection measurement 47

Phenomena 47

Quantities to describe reflection and transmission 48

Measuring geometries 49

The sample plane and influx geometry 50

Directional geometries 54

Quantities using different measuring geometries 55

Nonstandard geometries 55

Recommended geometry for transmission measurements 55

Standards of reflectance 57

Uniform chromaticity diagram and uniform color spaces 58

Uniform chromaticity diagram, CIE 1976 UCS diagram 59

CIE 1976 uniform color spaces 60

CIE 1976 (L*a* b*) color space, CIELAB color space 61

Cie 1976 (L* u* v*) Color Space, Cieluv Color Space 64

Descriptors of chromaticity 65

Dominant/complementary wavelength and purity 65

Correlated color temperature 67

Whiteness 68

Metamerism 70

Special metamerism index: change in illuminant 71

Special metamerism index: change in observer 72

Summary 74

Appendix A 74

Appendix B 75

References 76

4 CIE Color Difference Metrics 79
Klaus Witt

Introduction 79

MacAdam’s experiments on variable stimuli 80

Adams’ and Nickerson’s contribution to color difference evaluation 82

Constant stimuli experiments 83

CIE 1976 color difference formulas 84

Testing and improving CIELAB 88

Collection of new datasets 91

Development of CIEDE 2000 91

Further developments 97

References 98

5 Spectral Color Measurement 101
Yoshi Ohno

Introduction 101

General practice in spectral color measurements 102

Type of instruments 102

Use of spectroradiometers for light source color measurement 103

Irradiance mode 104

Radiance mode 105

Total flux mode 106

Colorimetric calculation 107

Use of spectrophotometers for object color measurements 107

Geometries for reflectance color measurement 108

Color calculation 109

Critical parameters of spectrometers for color measurement 109

Sampling interval and bandpass of instruments 109

Sampling interval for object color measurement 110

Effect of bandpass in object color measurement 112

Effect of bandpass and scanning interval in measurement of light sources 112

Wavelength scale error 116

Uncertainties in measured spectral values 118

Stray light in the monochromator 119

Other sources of error 122

Methods for corrections of error 123

Correction of bandpass error 123

ASTM E 308 123

Stearns and Stearns’ method 124

Extended method for bandpass correction 125

Summary for bandwidth and scanning interval requirements 127

Correction of stray light 128

Uncertainty analysis 129

Basic steps 130

Numerical method for sensitivity coefficient 131

Acknowledgment 132

References 132

6 Tristimulus Color Measurement of Self-Luminous Sources 135
János Schanda, George Eppeldauer, and Georg Sauter

Introduction 135

Basic structure of a tristimulus colorimeter 136

Input optics of a colorimeter for self-luminous objects 137

Illuminance-meter-type input optics 137

Luminance-meter-type input optics 138

Image-taking colorimeters 139

Spectral matching of the colorimeter 139

Electronics 142

Calibration 142

Calibration with a standard source 142

Calibration based on standard detectors 144

Introduction 144

The spectral responsivity based calibration method 144

Calibration and measurement considerations 145

Transfer of calibration 147

Uncertainty estimation of a tristimulus colorimeter measurement 148

Principle of the tristimulus calibration for a self-luminous object measuring tristimulus instrument 148

Numerical example for a tristimulus calibration 151

Calibration for selected spectral distributions 152

Glossary 154

Basic terms 154

Specific terms 155

References 156

7 Color Management 159
Ján Morovič and Johan Lammens

Introduction 159

Color reproduction objectives 160

Viewing a pair of colors 161

Conceptual stages of color reproduction 163

Device color spaces 164

Device characterization and calibration 165

Color appearance model 166

Color and image enhancement 166

Color gamut mapping 167

Completing the process 168

The ICC color management framework 168

sRGB color management 170

Challenges of color management 171

Does color need to be managed? 172

Analog color management 174

Watercolor reproduction scenario 176

Original to scan 177

Challenges of scanner characterization 178

Scanner characterization models 180

Scanner ICC profiles 181

Scanned watercolor 182

Scan to display 182

Challenges of display characterization 183

Display characterization models and their implementation in profiles 183

Transforming scanned data to data for display 184

Editing and page layout 185

Proofing 188

Proof printer calibration 189

Proof printer characterization 190

Rendering intents for proofing 191

Evaluation of proof prints 192

Challenges and opportunities 193

Poster and leaflet production 194

Future opportunities 195

Self-calibrating and self-profiling devices 195

Workflow automation 196

Automatic adaptation to viewing environment 198

Spatial processing 200

Smart CMMs 200

Multispectral imaging (CIE TC8-07) 202

Conclusion 202

Acknowledgments 202

References 203

8 Color Rendering of Light Sources 207
János Schanda

Introduction 207

The official CIE test sample method of color rendering evaluation 208

Recent investigations to update the color-rendering index calculation 211

Supplementary methods to describe color quality of light sources 213

Summary 214

References 215

Part III Advances in colorimetry

9 Color-Matching Functions: Physiological Basis 219
Françoise Viénot and Pieter Walraven

The link between colorimetry and physiology 219

The definition of cone fundamentals 220

Historical background 220

Decision by CIE 220

Available experimental data 220

State of the art in physiology 220

In vitro measurements 220

The principle of univariance 221

Dartnall nomogram: dilute pigment: effective transmission optical density 221

Available psychophysical measurements 222

Spectral sensitivity functions of dichromats and the König hypothesis 222

Spectral sensitivity functions of isolated cone mechanisms 222

Short description of colorimetric databases 223

Extending colorimetric data from 10 field to any field size from 10 to 1 226

The cone fundamentals 226

Linear transformation that yields the 10 cone fundamentals 227

Validation of cone fundamentals 228

Calculation scheme from dilute photopigment spectral absorbance to color-matching functions, and reverse 228

Lens and other preretinal media 228

Macular pigment 229

Calculation scheme from dilute photopigment spectral absorbance to cone spectral absorbance, and reverse 229

S-cone fundamental from 510 to 615 nm (2 field and 10 field) 231

Extension to any field size 231

The aging observer 232

The calculation of tristimulus values 233

CIE recommendations from CIE and final tables 234

Discussion and perspectives 235

An isoluminant fundamental chromaticity diagram 235

Units and luminous efficiency function 235

The l, s chromaticity diagram 236

A CIE-like chromaticity diagram 237

Individual variations 238

At the receptoral level 238

Postreceptoral processing: weighting L-signals and M-signals for luminance 238

Examples of applications: The future 238

Color vision deficiencies 238

Observer metamerism 239

Color differences 239

Color appearance models 239

Conclusion 240

Acknowledgments 240

References 240

10 Open Problems on the Validity of Grassmann’s Laws 245
Michael H. Brill and Alan R. Robertson

Definition of the problem 245

Historical review 246

Theoretical approaches 248

Generalizations of grassmann additivity 248

Theory of transformation of primaries 250

Numerical experiment 251

Summary of the method 251

Results and discussion 252

Conclusion 254

Activities of CIE TC 1–56 254

The future 257

References 258

11 CIE Color Appearance Models and Associated Color Spaces 261
M. Ronnier Luo and Changjun li

Introduction 261

Viewing conditions 262

Stimulus 262

Proximal field 263

Background 263

Surround 263

Adapting field 263

Color appearance datasets 263

Chromatic adaptation transforms 264

Light and chromatic adaptation 264

Physiological mechanisms 264

Chromatic adaptation 264

Development of the CAT02 used in CIECAM 02 266

CIE Color appearance models 268

CIECAM97s 269

Ciecam 02 270

Color appearance phenomena 271

Chromatic adaptation 271

Hunt effect 273

Stevens effect 274

Surround effect 275

Lightness contrast effect 276

Helmholtz–Kohlrausch effect 276

Helson–Judd effect 277

Uniform Color Spaces based on CIECAM 02 277

CIECAM02-based color spaces 277

Comparing the performance of the new UCSs with some selected color models 278

Conclusions 280

References 281

Appendix A: chromatic adaptation transform: CAT 02 284

Part 1: Forward Mode 284

Part 2: Reverse Mode 285

Appendix B: CIE color appearance model: CIECAM 02 286

Part 1: The Forward Mode 286

Part 2: The Reverse Mode 291

12 Image Appearance Modeling 295
Garrett M. Johnson and Mark D. Fairchild

Introduction 295

From simple to complex color appearance 296

Image appearance modeling 300

The general iCAM framework for image appearance 301

Specific implementations of image appearance models: high-dynamic range tone-mapping 308

Testing high-dynamic range rendering algorithms 312

An implementation of image appearance for calculating image differences 314

Spatial frequency adaptation 318

Calculating image differences 319

Conclusions and future considerations 320

References 321

13 Spatial and Temporal Problems of Colorimetry 325
Eugenio Martinez–Uriegas

Introduction 325

Radiometry, photometry, colorimetry, and human vision 325

Standards of color: the role of biology and psychophysics 326

Spatial and temporal constraints of colorimetry: a selective overview 329

Spectral, spatial, and temporal dimensions of visible light 329

Classical separation of spatial, temporal, and color vision 330

Two examples of spatial limitations of colorimetry 331

Representation of spatial and temporal properties of visible light 335

Spatial and temporal distributions of visible light 335

Detection and discrimination thresholds 338

Visual multiplexing of spatiotemporal chromatic and achromatic information 340

Developing CSF standards 342

General approach: data-based or theory-based standard 342

Initial results 343

Multiscale colorimetry: a spatiotemporal path forward 345

Example of multiscale image decomposition 345

Scale-shifting conjecture 348

Multiscale colorimetry: a spatiotemporal path forward 348

Summary thoughts 352

References 352

14 The Future of Colorimetry in the CIE 355
Robert W.G. Hunt

Introduction 355

Color matching 355

Color difference 357

Color appearance 359

Sources of funds 362

References 362

Appendix 1 Measurement Uncertainty 365
Georg Sauter

Introduction 365

Definitions and types for the evaluation of uncertainty 366

Definitions of terms 366

Types for the evaluation of uncertainty 367

Model of evaluation of uncertainty 368

Monte Carlo method 369

Model with two or more output quantities 371

Expanded uncertainty 373

Steps for evaluating uncertainty 373

Practical examples 374

Determination of the spectral irradiance of a source 375

Principle of a spectral irradiance measurement 375

Operation of a spectral irradiance standard 376

Mechanical alignments 378

Uncertainty Budget 379

Determination of f1 0 values 383

Uncertainty of f1 0 values with Monte Carlo method 386

References 387

Appendix 2 Uncertainties in Spectral Color Measurement 389
James L. Gardner

Introduction 389

Tristimulus values 390

Uncertainty propagation 392

Tristimulus uncertainties by component 393

Random component effects 394

Systematic component effects 394

Propagation from tristimulus uncertainties to colour-value uncertainties 396

Methods of calculation for color triplets 397

(x,y,Y) color coordinates 397

(u,v,Y) color coordinates 398

(u’, y’, Y) color coordinates 398

(L *, a*, b*) color coordinates 399

(L*, C*, h) color coordinates (based on a*, b*) 399

(L*, u*, v) Color Coordinates 400

(L*, C*, h) Color Coordinates (based on U*, V*) 401

(L*, s*, h) Color Coordinates (based on U*, V*) 401

Spectral measurement as a transfer 401

Uncertainty of the reference values 402

Relative scaling of the measured spectral values 403

Random scaling components 403

Systematic scaling components 403

Offsets in the spectral values 403

Random offset components 404

Systematic offset components 404

Wavelength errors 404

Random wavelength offsets 405

Systematic wavelength offsets 405

Determining measurement components 405

Background offsets 406

Noise versus drift 406

Source noise 407

Band-limited spectra 407

Wavelength uncertainties 407

Nonlinearity 408

Corrections 408

Conclusion 409

References 409

Appendix 3 Use of CIE Colorimetry in the Pulp, Paper, and Textile Industries 411
Robert Hirschler and Joanne Zwinkels

Introduction 411

Pulp and paper applications 411

Introduction 411

Beneficiaries of CIE colorimetry 413

CIE illuminant C and CIE standard geometry d/ 0 413

Other CIE standard illuminants and standardized light sources 415

CIE color spaces 416

CIE reference standards 416

CIE whiteness and tint equations 418

Harmonized Terminology 419

Driving force in the development of CIE colorimetry 419

Establishment of new CIE technical committees 419

Practical simulator of illuminant D 65 420

Future needs 422

Conclusion 422

Textile applications 423

Introduction 423

CIELAB color space and its derivations 423

Characterization of the buildup of colorants and of colorant combinations 423

Standard Depth (SD) 424

Color difference evaluation 425

Shade sorting, tapering 425

Fastness evaluation 427

Determination of whiteness 427

Recipe formulation 429

Future needs 429

Conclusion 430

References 430

Appendix 4 List of CIE Publications 435

Recommendations 435

Standards 435

Technical committee reports 436

Proceedings of the sessions 441

Discs and other publications 442

Special publications 442

CIE publications on CD-ROM 443

Glossary 445

Index 453