Steve Wright

Color Science and Digital Imaging (eBook, ePUB)

An Essential Guide for Visual Effects Artists, Filmmakers, and Photographers

• Format: ePub

Produktbeschreibung

This book, written by a leading expert in the field of visual effects, demystifies the complex subject of color science and how it should be managed from project ideation to completion.

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Produktdetails

• Verlag: Taylor & Francis
• Erscheinungstermin: 21. November 2024
• Englisch
• ISBN-13: 9781040127001
• Artikelnr.: 72259460

Autorenporträt

Steve Wright, an award-winning VFX pioneer and renowned educator, is the published author of two popular books: Digital Compositing for Film and Video and Compositing Visual Effects. In 2005, his attention turned full-time to educating the next generation of VFX practitioners, imparting his vast technical knowledge gleaned from 30-plus years of production experience. His love of digital imaging technology and color science is the mainstay of his training website, FX Ecademy.

Inhaltsangabe

Foreword...........................................................................................xv Preface............................................................................................. xix Acknowledgments............................................................................ xxiii Introduction: The Five Spaces of the Digital Imaging Pipeline...........1 Chapter 1 - World Space ..............................................................5 1.1 The Nature of Light....................................................................6 1.1.1 Wavelength............................................................................6 1.1.2 Amplitude..............................................................................7 1.1.3 Phase....................................................................................8 1.1.4 Polarization............................................................................8 1.1.5 Monochromatic Light.............................................................9 1.1.6 Coherent Light.......................................................................9 1.1.7 Particles............................................................................... 10 1.1.8 The Inverse Square Law...................................................... 10 1.1.9 Interior vs. Exterior Lighting.................................................. 11 1.2 Measuring Light...................................................................... 11 1.2.1 Candela (cd): The Brightness of a Light Source................... 12 1.2.2 Lumen (lm): The Total Amount of Incident Light................... 12 1.2.3 Lux (lx): How Brightly a Scene is Lit..................................... 12 1.2.4 Other Units.......................................................................... 13 1.3 Dynamic Range........................................................................ 13 1.3.1 Brightness vs. Luminance.................................................... 14 1.3.2 What is Dynamic Range?..................................................... 14 1.3.3 Stops................................................................................... 16 1.4 A Color Science Moment........................................................ 16 1.4.1 Emission Spectrums............................................................ 17 1.4.2 Spectral Reflectance............................................................ 17 1.4.3 Color Stimulus..................................................................... 18 1.5 Light Sources......................................................................... 19 1.5.1 Emission Spectrums............................................................ 19 1.5.2 Color Temperature...............................................................21 1.5.3 Standard Illuminants............................................................23 1.6 Surface Interactions with Light................................................ 24 1.6.1 Spectral Reflectance............................................................ 24 1.6.2 Diffuse vs. Specular Reflections...........................................26 1.7 Exotic Surface Interactions with Light.....................................27 1.7.1 Scattering............................................................................27 1.7.2 Polarized Light.....................................................................29 1.7.3 The Fresnel Effect................................................................30 1.7.4 Color from Interference........................................................32 1.7.5 Dichroic Filters.....................................................................33 1.8 How We See the World.........................................................33 1.8.1 Color Perception..................................................................34 1.8.2 CIE xy-chromaticity Diagram...............................................35 1.8.3 Our Visual Response...........................................................37 1.8.4 Adaptation...........................................................................38 1.8.4.1 General Brightness Adaptation.............................39 1.8.4.2 Lateral Brightness Adaptation...............................39 1.8.4.3 Chromatic Adaptation...........................................40 1.8.5 Calculating Luminance.........................................................40 1.8.6 Metamers............................................................................42 1.9 Conclusion.......................................................................................43 Chapter 2 - Camera Space ....................................................................... 45 2.1 Camera Perceptions of Color...........................................................46 2.1.1 Spectral Sensitivity..............................................................46 2.1.2 Camera Gamuts..................................................................48 2.1.3 Converting Light to Digits.....................................................48 2.1.4 The Debayer Process..........................................................49 2.1.5 Camera Imaging Math......................................................... 51 2.1.6 Light Sources......................................................................52 2.1.6.1 Color Temperature................................................52 2.1.6.2 Spectral Emissions...............................................53 2.1.7 CCD vs. CMOS...................................................................54
2.2 Space and Time...............................................................................56 2.2.1 Resolution...........................................................................56 2.2.2 ISO......................................................................................57 2.2.3 Speed..................................................................................57 2.2.4 Sensor Crop........................................................................59 2.2.5 Sensor Size.........................................................................60 2.2.6 Anamorphic Formats...........................................................62 2.2.6.1 Cinemascope 2.39................................................62 2.2.6.2 HDTV 1.33............................................................63 2.3 Camera Dynamic Range..................................................................63 2.3.1 Clipping...............................................................................64 2.3.2 Bit Depth.............................................................................65 2.4 Video Standards..............................................................................66 2.4.1 Resolutions..........................................................................66 2.4.1.1 HDTV Standards ....................................................................66 2.4.1.2 UHDTV Standards ....................................................................67 2.4.2 Scan Modes........................................................................67 2.4.2.1 Progressive Scan..................................................67 2.4.2.2 Interlaced Scan.....................................................67 2.4.2.3 History..................................................................69 2.4.3 Frame Rates........................................................................70 2.5 Output Options................................................................................ 71 2.6 Camera Artifacts..............................................................................72 2.6.1 Noise...................................................................................72 2.6.2 Rolling Shutter..................................................................... 74 2.6.3 DSLR Rolling Shutter...........................................................75 2.6.4 Vignetting............................................................................75 2.7 Lens Artifacts...................................................................................76 2.7.1 Lens Distortion....................................................................78 2.7.2 Spherical Aberration............................................................78 2.7.3 Chromatic Aberration...........................................................79 2.7.4 Depth of Field......................................................................79 2.7.5 Veiling Glare.........................................................................80 2.7.6 Lens Flare............................................................................80 2.7.7 Bokeh..................................................................................81 2.7.8 The Swirly Bokeh.................................................................81 2.8 The DIT............................................................................................82 2.8.1 On-Set Support...................................................................82 2.8.2 Data Management...............................................................83 2.8.3 Color Grading......................................................................83 2.8.4 Post-Production Liaison.......................................................83 2.9 Virtual Production............................................................................84 2.9.1 How it Works.......................................................................84 2.9.2 The Promise........................................................................85 2.9.3 The Problems......................................................................86 2.10 What about 35 mm Film?................................................................87 2.10.1 Composition........................................................................87 2.10.2 Frame Rate..........................................................................88 2.10.3 Color Gamut........................................................................88 2.10.4 Grain....................................................................................89 2.10.5 A Softer Look......................................................................89 2.10.6 No Rolling Shutter................................................................90 2.10.7 Color Temperature...............................................................90 2.11 Conclusion.......................................................................................91 Chapter 3 - Storage Space ....................................................................... 93 3.1 Image Structure...............................................................................94 3.1.1 Pixels...................................................................................94 3.1.2 Bit Depth.............................................................................95 3.1.3 Channels.............................................................................97 3.1.4 Deep Data...........................................................................98 3.1.5 Metadata...........................................................................100 3.2 Compression Strategies................................................................. 101 3.2.1 Reduced Bit Depth............................................................ 102 3.2.2 Color Subsampling............................................................ 104 3.2.2.1 Luminance and Chrominance............................. 105 3.2.2.2 Subsampling Schemes....................................... 105 3.2.3 Discrete Cosine Transform (DCT)....................................... 107 3.2.4 MPEG................................................................................ 109 3.2.4.1 Spatial Compression........................................... 109 3.2.4.2 Temporal Compression....................................... 110 3.2.4.3 Summary............................................................ 110 3.2.5 Graphics Lossless Compression........................................111 3.2.5.1 RLE Compression................................................111 3.2.5.2 LZW Compression.............................................. 112 3.3 Codecs.......................................................................................... 112 3.3.1 H.264................................................................................ 113 3.3.2 H.265.................................................................................114 3.3.3 JPEG 2000.........................................................................114
3.3.4 ProRes.............................................................................. 115 3.3.5 DNxHD.............................................................................. 115 3.4 Containers..................................................................................... 116 3.4.1 MOV.................................................................................. 116 3.4.2 MP4................................................................................... 116 3.4.3 AVI......................................................................................117 3.4.4 Summary............................................................................117 3.5 Log Images.....................................................................................117 3.5.1 Why Log?.......................................................................... 118 3.5.2 What is Log Data?............................................................. 120 3.5.3 Data Point Distribution....................................................... 121 3.5.4 How Log Images Are Created............................................ 122 3.5.5 Log for Photography.......................................................... 123 3.6 Cinema Export Options................................................................. 125 3.6.1 Camera RAW..................................................................... 125 3.6.2 Camera Log....................................................................... 126 3.6.3 Compressed Exports........................................................ 126 3.7 Cinema File Formats...................................................................... 127 3.7.1 EXR................................................................................... 128 3.7.2 DPX................................................................................... 129 3.7.3 ProRes.............................................................................. 129 3.7.4 DNxHR.............................................................................. 130 3.7.5 Archival.............................................................................. 130 3.8 Photography Export Options.......................................................... 131 3.8.1 Camera Raw...................................................................... 131 3.8.2 Log Recording (Camera Log)............................................. 131 3.8.3 Compressed Exports........................................................ 132 3.9 Photography File Formats.............................................................. 132 3.9.1 DNG.................................................................................. 133 3.9.2 JPEG................................................................................. 133 3.9.3 PSD................................................................................... 133 3.9.4 PNG.................................................................................. 133 3.9.5 TIFF................................................................................... 133 3.9.6 WebP................................................................................ 134 3.9.7 HEIF.................................................................................. 134 3.9.8 Do Not Use........................................................................ 134 3.10 Conclusion..................................................................................... 135 Chapter 4 - Work Space ...........................................................................137 4.1 Color Theory.................................................................................. 138 4.1.1 Additive Color.................................................................... 138 4.1.2 Subtractive Color............................................................... 139 4.2 Color Models................................................................................. 140 4.2.1 RGB.................................................................................. 142 4.2.2 HSL................................................................................... 142 4.2.3 YCbCr............................................................................... 143 4.2.4 CMYK................................................................................ 144 4.3 Color Spaces................................................................................. 145 4.3.1 CIE Chromaticity Diagram.................................................. 146 4.3.2 Primary Chromaticities....................................................... 148 4.3.3 White Points...................................................................... 148 4.3.4 The Transfer Function........................................................ 149 4.3.5 Color Gamuts.................................................................... 151 4.3.6 Pointer's Gamut................................................................. 153 4.3.7 CIEXYZ and CIELAB (CIE L*a*b*)........................................ 153 4.4 Linear vs. Gamma Corrected......................................................... 155 4.4.1 What is Gamma, Exactly?.................................................. 157 4.4.2 Monitor Gamma................................................................. 159 4.4.3 Gamma Correction............................................................ 160 4.4.4 Gamma-Corrected Images................................................ 160 4.4.5 Linear Images.................................................................... 161 4.5 Integer vs. Float............................................................................. 162 4.5.1 Integer............................................................................... 163 4.5.2 Float.................................................................................. 163 4.6 LDR vs. HDR Images..................................................................... 165 4.7 Choosing Your Work Space........................................................... 166 4.7.1 Working in Linear............................................................... 167 4.7.2 Working in Display Space.................................................. 168 4.7.3 Working in ACES............................................................... 169 4.7.4 Working in Log.................................................................. 170 4.7.4.1 Picking the Right Curve....................................... 171 4.7.4.2 Going Negative................................................... 172 4.7.4.3 Limited Dynamic Range...................................... 172 4.8 Photography Work Spaces.............................................................174 4.8.1 sRGB..................................................................................174 4.8.2 Adobe RGB....................................................................... 175 4.8.3 ProPhoto RGB................................................................... 176
4.8.4 SWOP............................................................................... 176 4.9 Archiving........................................................................................ 178 4.9.1 OpenEXR.......................................................................... 179 4.9.2 DPX................................................................................... 179 4.9.3 Camera Raw...................................................................... 179 4.10 Conclusion..................................................................................... 179 Chapter 5 - Display Space .......................................................................181 5.1 Display Attributes........................................................................... 182 5.1.1 Spectral Emissions............................................................ 182 5.1.2 Color Gamut...................................................................... 183 5.1.3 White Point........................................................................ 184 5.1.4 Transfer Function (Gamma)................................................ 184 5.1.5 Brightness......................................................................... 184 5.1.6 Contrast Ratio................................................................... 185 5.1.7 Bit Depth........................................................................... 186 5.1.8 Frame Rates...................................................................... 187 5.1.9 Refresh Rates.................................................................... 188 5.1.10 Calibration......................................................................... 188 5.1.11 Viewing Surround.............................................................. 189 5.2 SDR vs. HDR................................................................................. 191 5.2.1 Cinema.............................................................................. 192 5.3 HDR Display Formats..................................................................... 192 5.3.1 Hybrid Log Gamma (HLG)................................................. 193 5.3.2 The Perceptual Quantizer (PQ)........................................... 193 5.4 Display Devices.............................................................................. 195 5.4.1 Flat-Panel Display Construction......................................... 195 5.4.2 Workstation Monitors......................................................... 196 5.4.2.1 Specs................................................................. 196 5.4.3 HDTV................................................................................. 197 5.4.3.1 Specs................................................................. 198 5.4.4 Digital Cinema................................................................... 198 5.4.4.1 Specs................................................................. 199 5.5 Coming Soon.................................................................................200 5.5.1 UHDTV..............................................................................200 5.5.1.1 Specs.................................................................202 5.5.2 Digital Cinema 2.0..............................................................203 5.5.2.1 RGB Lasers........................................................203 5.5.2.2 Laser Phosphor..................................................203 5.5.2.3 LED Screens.......................................................204 5.5.2.4 High Frame Rate Movies.....................................204 5.5.2.5 Specs.................................................................205 5.6 Conclusion.....................................................................................205 Chapter 6 - Color Management ............................................................ 207 6.1 Color Grading................................................................................208 6.1.1 1D LUTs.............................................................................209 6.1.2 3D LUTs.............................................................................209 6.1.3 Grading Operations........................................................... 210 6.1.4 Range Controls.................................................................. 212 6.1.5 Secondary Color Grading.................................................. 213 6.1.6 Scopes.............................................................................. 215 6.1.6.1 Waveform Monitor............................................... 216 6.1.6.2 Vectorscope........................................................ 217 6.1.6.3 Histogram........................................................... 217 6.1.7 Color Grading in Log......................................................... 218 6.1.8 Using Histograms..............................................................220 6.1.8.1 Color Matching...................................................221 6.1.8.2 Increasing Contrast.............................................221 6.2 Digital Intermediate (DI)..................................................................222 6.2.1 Conforming........................................................................222 6.2.2 The Mastering Process......................................................223 6.2.3 Visual Effects..................................................................... 224 6.2.4 Deliverable File Formats.....................................................225 6.3 ICC Profiles....................................................................................226 6.3.1 How ICC Profiles Work......................................................227 6.3.2 Color Space Conversions..................................................229 6.3.3 Gamut Mapping................................................................229 6.4 Working with Supersized Gamuts.................................................. 231 6.4.1 Viewing Supersized Gamuts.............................................. 231 6.4.2 Remapping Supersized Gamuts........................................232 6.4.2.1 Large to Small Gamuts.......................................232 6.4.2.2 Small to Large Gamuts.......................................233 6.4.3 Tone Mapping.............................................