Standard Colorimetry

Society of Dyers and Colourists xv Preface xvii 1 Generalities on Colour and Colorimetry 1 1.1 Colour 1 1.2 Colorimetry 2 References 4 Bibliography 4 2 Optics for Colour Stimulus 5 2.1 Introduction 5 2.2 Electromagnetic Waves 7 2.3 Photons 11 2.4 Radiometric and Actinometric Quantities 11 2.5 Inverse Square Law 14 2.6 Photometric Quantities 14 2.7 Retinal Illumination 16 References 16 Bibliography 16 3 Colour and Light–Matter Interaction 17 3.1 Introduction 17 3.1.1 Luminous Colours 17 3.1.2 Non]luminous Colours 18 3.1.3 Light Phenomena and Body Appearance 18 3.2 Light Sources 19 3.3 Planckian Radiator 20 3.4 Light Regular Reflection and Refraction 21 3.4.1 Snell’s Laws 22 3.4.2 Fresnel’s Laws 23 3.5 Light Scattering 24 3.5.1 Lambertian Diffusion 25 3.5.2 Light Scattering on a Rough Surface 25 3.5.3 Light Scattering in an Optically Heterogeneous Medium 26 3.6 Light Absorption and Colour Synthesis 28 3.6.1 Simple Subtractive Synthesis 28 3.6.2 Complex Subtractive Synthesis 28 3.7 Fluorescence 29 3.8 Transparent Media 30 3.8.1 Internal Transmittance of a Medium 30 3.8.2 Total Transmittance and Total Reflectance 32 3.9 Turbid Media 33 3.9.1 Two]Flux Model of Kubelka–Munk 34 3.9.2 Saunderson’s Equation 36 3.9.3 Colorant Characterization and Formulation 38 3.10 Ulbricht’s Integration Sphere 41 References 43 Bibliography 44 4 Perceptual Phenomenology of Light and Colour 45 4.1 Introduction 45 4.2 Perceived Colours, Categorization and Language 46 4.3 Light Dispersion and Light Mixing 47 4.3.1 Newton’s Prism Experiment, Colour Wheel and Colour Attributes 48 4.3.2 Maxwell’s Disk Experiment 50 4.4 Unique Hues, Colour Opponencies and Degree of Resemblance 52 4.5 Colour Similitude 55 4.6 Unrelated and Related Colours 56 4.6.1 Relative Attributes 56 4.7 Colour Interactions 57 References 65 5 Visual System 67 5.1 Introduction 67 5.2 Eye Anatomy and Optical Image Formation 68 5.3 Eye and Pre]retina Physics 72 5.4 Anatomy of the Retina 74 5.4.1 Retina Layers 76 5.4.2 Fovea 77 5.4.3 Foveola 78 5.4.4 Extra Fovea 78 5.4.5 Macula Lutea 79 5.4.6 Rod and Cone Distribution 79 5.5 From the Retina to the Brain 80 5.5.1 Scotopic Vision 80 5.5.2 Photopic Trichromatic Vision 81 5.5.3 Rushton’s Univariance Principle and Photoreceptor Activation 82 5.5.4 Horizontal Cells 83 5.5.5 Bipolar Cells 83 5.5.6 Amacrine Cells 84 5.5.7 Ganglion Cells and Visual Pathways 84 5.5.8 From the Ganglion Cells to the Visual Cortex 85 5.6 Visual System and Colorimetry 87 Bibliography 88 References 88 6 Colour]Vision Psychophysics 91 6.1 Introduction 91 6.1.1 Psychophysics and Physiology 91 6.1.2 Visual Judgement 92 6.1.3 Modes of Colour Appearance and Viewing Situations 93 6.1.4 Colour Stimuli 95 6.1.5 Colour]Attribute Matching 98 6.1.6 Visual Detection Threshold and Sensitivity 99 6.1.7 Scaling of Colour Attributes 100 6.2 Adaptation 103 6.2.1 Brightness Adaptation 105 6.2.2 Threshold in Dark Adaptation 106 6.3 Absolute Thresholds in Human Vision 108 6.4 Absolute Threshold and Spectral Sensitivity in Scotopic and Photopic Visions 108 6.4.1 Silent Substitution Method 109 6.5 Luminous Efficiency Function 113 6.5.1 Abney Additivity Law and Luminance 114 6.6 Light Adaptation and Sensitivity 116 6.7 Weber’s and Fechner’s Laws 118 6.7.1 Contrast Sensitivity 119 6.7.2 Fechner’s Scaling 119 6.8 Stevens’ Law 119 6.8.1 Brightness Scaling and Stevens’ Law 119 6.9 Fechner’s and Stevens’ Psychophysics 121 6.10 Wavelength Discrimination 121 6.11 Saturation Discrimination and Least Colorimetric Purity 123 6.12 Rushton’s Univariance Principle and Scotopic Vision 124 6.13 Tristimulus Space 125 6.13.1 Rushton’s Univariance Principle and Grassmann’s Laws in Photopic Vision 126 6.13.2 Metamerism 130 6.13.3 Chromaticity 131 6.13.4 Reference Frames in Tristimulus Space 132 6.13.5 Measurement of the Colour-Matching Functions in the RGB Reference Frame 134 6.13.6 Luminance and Exner-Schrödinger’s ‘Helligkeit’ Equation 139 6.13.7 Dichromats and Fundamental Reference Frame 141 6.13.8 Newton’s Centre]of]Gravity Rule and Chromaticity]Diagram Properties 145 6.14 Lightness Scales 149 6.15 Helmholtz-Kohlrausch Effect 150 6.16 Colour Opponencies and Chromatic Valence 153 6.17 MacAdam’s Chromatic Discrimination Ellipses 155 6.18 Perceived Colour Difference 156 6.19 Abney’s and Bezold-Brücke’s Phenomena 161 6.20 Chromatic Adaptation and Colour Constancy 164 6.20.1 Asymmetric Colour Matching 165 6.20.2 Empirical Data 166 6.20.3 Von Kries’s Coefficient Law 166 6.20.4 Retinex 168 6.21 Colour]Vision Psychophysics and Colorimetry 170 References 171 7 CIE Standard Photometry 177 7.1 Introduction 177 7.2 History of the Basic Photometric Unit 180 7.3 CIE 1924 Spectral Luminous Efficiency Function 180 7.4 CIE 1924 and CIE 1988 Standard Photometric Photopic Observers 181 7.5 Photometric and Radiometric Quantities 182 7.6 CIE 1951 Standard Scotopic Photometric Observer 185 7.7 CIE 2005 Photopic Photometric Observer with 10° Visual Field 185 7.8 CIE Fundamental Photopic Photometric Observer with 2°/10° Visual Field 185 7.8.1 Photopic Spectral Luminous Efficiency Functions for the 2° Fundamental Observer 186 7.8.2 Photopic Spectral Luminous Efficiency Functions for the 10° Fundamental Observer 186 References 186 8 Light Sources and Illuminants for Colorimetry 189 8.1 Introduction 189 8.2 Equal]Energy Illuminant 190 8.3 Blackbody Illuminant 191 8.4 CIE Daylights 193 8.5 CIE Indoor Daylights 195 8.6 CIE Standard Illuminants 196 8.7 CIE Light Sources: A, B and C 197 8.8 CIE Sources for Colorimetry 198 8.9 CIE Illuminants: B, C and D 199 8.10 Fluorescent Lamps 199 8.10.1 Typical Fluorescent Lamps 199 8.10.2 New Set of Fluorescent Lamps 200 8.11 Gas]Discharge Lamps 204 8.12 Light]Emitting Diodes 205 References 208 9 CIE Standard Psychophysical Observers and Systems 209 9.1 Introduction 209 9.2 CIE 1931 Standard Colorimetric System and Observer 210 9.2.1 CIE 1931 RGB Reference Frame and WDW Chromaticity]Coordinates Normalization 211 9.2.2 CIE 1931 XYZ Reference Frame 214 9.3 CIE 1964 (Supplementary) Standard Colorimetric Observer/System (10°]Standard Colorimetric Observer) 218 9.4 CIE 1989 Standard Deviate Observer/System 221 9.5 Vos’ 1978 Modified Observer for 2° Visual Field 221 9.5.1 Smith–Pokorny’s Cone Fundamentals 223 9.5.2 Vos’ 1978 2° Fundamental Observer Data and MacLeod–Boynton’s Chromaticity Diagram 223 9.6 CIE Standard Stockman]Sharpe’s ‘Physiologically Relevant’ Fundamentals and XYZ Reference Frame 224 9.6.1 XFYFZF and XF,10YF,10ZF,10 Reference Frames 226 9.6.2 MacLeod-Boynton’s Tristimulus Space and Chromaticity Diagram 229 9.7 CIE Colorimetric Specification of Primary and Secondary Light Sources 232 References 234 10 Chromaticity Diagram from Newton to the CIE 1931 Standard System 237 10.1 Introduction 237 10.2 Newton and the Centre of Gravity Rule 237 10.3 Material Colours and Impalpable Colours in the Eighteenth Century 243 10.4 Physiological Intuitions and the Centre of Gravity Rule – Young, Grassmann, Helmholtz, Maxwell and Schrödinger 245 10.5 Conclusion 251 References 251 11 CIE Standard Psychometric Systems 253 11.1 Introduction to Psychometric Systems in Colour Vision 253 11.2 CIE Lightness L* 254 11.3 Psychometric Chromaticity Diagrams and Related Colour Spaces 255 11.3.1 CIE 1960 (u, v) UCS Psychometric Chromaticity Diagram 255 11.3.2 CIE 1964 (U*, V*, W*) Uniform Colour Space – CIEUVW Colour Space 257 11.3.3 CIE 1976 (u′, v′) UCS Psychometric Chromaticity Diagram 257 11.3.4 CIE 1976 (L*, u*, v*) Colour Space – CIELUV Colour Space 259 11.3.5 CIE 1976 (L*, a*, b*) Colour Space – CIELAB Colour Space 261 11.4 Colour Difference Specification 264 11.4.1 Colour Difference Data 264 11.4.2 CIE 1976 Colour]Difference Formulae 265 11.4.3 CMC(l : c) Colour]Difference Formula 266 11.4.4 CIE 1994 Colour]Difference Formula 267 11.4.5 CIEDE2000 Total Colour]Difference Formula 268 11.4.6 Small Colour Differences in OSA]UCS Space 270 11.4.7 Metamerism Indices 270 11.4.8 Daylight]Simulator Evaluation and ‘Special Metamerism Index: Change in Illuminant’ 273 11.5 Conclusion 276 References 276 12 Instruments and Colorimetric Computation 279 12.1 Introduction 279 12.2 Reflection and Transmission Optical]Modulation 282 12.2.1 Absolute Quantities of Optical]Modulation 282 12.2.2 Relative Quantities of Optical]Modulation 283 12.3 Spectroradiometric and Spectrophotometric Measurements 296 12.3.1 Introduction to the Spectrometer 296 12.3.2 Instrumental Convolution 303 12.3.3 Deconvolution 308 12.4 Colorimetric Calculations 309 12.4.1 CIE Colour Specification 309 12.4.2 Relative Colour Specification 310 12.4.3 Deconvolution 312 12.4.4 Interpolation 313 12.4.5 Extrapolation 315 12.5 Uncertainty in Colorimetric Measurements 315 12.5.1 Laws of Propagation of Uncertainty 317 12.5.2 Uncertainty Computation 318 12.6 Physical Standards for Colour]Instrument Calibration 320 References 322 13 Basic Instrumentation for Radiometry, Photometry and Colorimetry 325 13.1 Introduction 325 13.2 Lighting Cabinet 327 13.3 Visual Comparison Colorimeter 329 13.4 Instruments with Power Spectral Weighting Measurement 330 13.4.1 Photometric Instruments 330 13.4.2 Colorimetric Instruments 332 13.5 Instruments for Measurements with Spectral Analysis 336 13.5.1 Spectroradiometer 336 13.5.2 Spectrophotometer 337 13.5.3 Multiangle Spectrophotometers 337 13.5.4 Fibre]Optic]Reflectance Spectroscopy (FORS) 338 13.6 Glossmeter 341 13.7 Imaging Instruments 343 13.7.1 Imaging Photometer 343 13.7.2 Colorimetric Camera 344 13.7.3 Multispectral and Hyperspectral Camera 344 References 346 14 Colour]Order Systems and Atlases 349 14.1 Introduction 349 14.2 Colour Solid, Optimal Colours and Full Colours 351 14.2.1 MacAdam’s Limit 354 14.3 Ostwald’s Colour]Order System and Atlas 354 14.3.1 Ostwald’s Hue Circle with Temperate Scale 355 14.3.2 Ostwald’s Semichrome 356 14.3.3 Ostwald’s Blackness, Whiteness and Purity 357 14.3.4 Ostwald’s Atlas 358 14.4 Munsell’s Colour]Order System and Atlas 360 14.4.1 Munsell’s Instruments 362 14.4.2 Chromatic Tuning Fork 362 14.4.3 Munsell’s Value and Grey Scale 364 14.4.4 Munsell’s Hue 365 14.4.5 Munsell’s Value in Coloured Scales 367 14.4.6 Colour Sphere and Munsell’s Colour Specification 367 14.4.7 Munsell’s Chroma 369 14.4.8 Colour Tree 369 14.4.9 Munsell’s System and CIE Chromaticity Specification 369 14.4.10 Helmholtz-Kohlrausch’s Effect and Abney’s Hue Shift Phenomenon in the Munsell Atlas 371 14.4.11 Munsell’s Colour Atlas 371 14.5 DIN 6264’s Colour]Order System and Atlas 372 14.6 OSA]UCS’s Colour]Order System and Atlas 374 14.6.1 OSA]UCS’s Lightness 376 14.6.2 OSA]UCS’s (g, j) Coordinates 377 14.6.3 OSA]UCS’s Colour Difference Formula 379 14.6.4 OSA]UCS’s Metrics 379 14.7 NCS’s Colour]Order System and Atlas 380 14.7.1 NCS’s Axioms 381 14.7.2 NCS’s Hue, Chromaticness and Nuance 382 14.7.3 Production of the NCS System and Visual Situation 384 14.7.4 Psychophysics and Psychometrics for NCS 384 14.7.5 Luminance Factor and NCS’s Whiteness Scale 385 14.7.6 NCS’s Atlas 387 References 387 15 Additive Colour Synthesis in Images 391 15.1 Introduction 391 15.2 Video Colour Image 392 15.2.1 RGB Colorimetry 395 15.2.2 Video Signal and γ Correction 397 15.2.3 Tristimulus Space and YIQ Reference Frame 401 15.2.4 sRGB System 404 15.2.5 Prints in the sRGB System 406 15.2.6 Camera, Photo]Site and Pixel 406 15.2.7 Spectral Sensitivities of Digital Cameras 409 15.3 Principles of Halftone Printing 412 15.4 Towards the Colorimetry of Appearance 419 References 420 16 Software (Software developed by Gabriele Simone) 423 16.1 Introduction to the Software 423 16.1.1 Software Installation 423 16.1.2 Data Files 425 16.2 Monitor 429 16.2.1 Monitor Setup 429 16.2.2 Visual Evaluation of Gamma (γ) 430 16.3 Colour]Vision Tests 432 16.4 Visual Contrast Phenomena 440 16.4.1 Simultaneous Brightness Contrast and Crispening 440 16.4.2 Simultaneous Brightness Contrast in Colour Scales 441 16.4.3 Brightness and Chromatic Contrast 442 16.4.4 After Image 442 16.5 Colour Atlases 443 16.5.1 Ostwald’s Atlas 444 16.5.2 Munsell’s Atlas 444 16.5.3 DIN’s Atlas 444 16.5.4 OSA]UCS’ Atlas 446 16.5.5 NCS’ Atlas 447 16.6 CIE 1976 CIELUV and CIELAB Systems 448 16.7 Cone Activation and Tristimulus 450 16.8 CIE Colorimetry 451 16.8.1 CIE Colour Specification 452 16.8.2 CIE Systems 456 16.8.3 Chromaticity Diagrams 459 16.8.4 Fundamental Observers 462 16.8.5 Dominant Wavelength and Purity 463 16.8.6 Tristimulus Space Transformations 463 16.8.7 Colour]Difference Formulae ΔE 464 16.8.8 CIE 1974 Colour Rendering Index Ra 465 16.9 Black Body and Daylight Spectra and Other CIE Illuminant Spectra 470 16.10 Additive Colour Synthesis 471 16.10.1 RGB Monitor, Additive Colour Mixture 472 16.10.2 Halftone CMY Printing 472 16.11 Subtractive Colorant Mixing 474 16.11.1 Two Pigment Mixture 475 16.11.2 Four Pigment Mixture 475 16.12 Spectral Data View and Download – Illuminant-Observer Weights 478 16.13 Save File Opening 478 References 480 Index 481