Digital Video


A Technical Introduction to Digital Video

Contents

Acknowledgments    vii

List of figures    xix

List of tables    xxv

Preface    xxvii

Formulas   xxviii
Luma vs Luminance   xxviii
CCIR vs ITU-R   xxviii
Standards   xxix
Layout and typography    xxix
Further reading   xxx

Basic principles    1

Imaging   1
Digitization   2
Pixel array   3
Spatiotemporal domains   4
Scanning notation   4
Viewing distance and angle   5
Aspect ratio   6
Frame rate, refresh rate   6
Motion portrayal   8
Raster scanning   8
Interlace   11
Scanning standards   12
Sync structure   13
Data rate   15
Data rate of digital video   15
Linearity   16
Perceptual uniformity   17
Noise, signal, sensitivity   17
Quantization   18
Frequency response, bandwidth   19
Bandwidth and data rate   20
Resolution   21
Resolution in film   21
Resolution in television   22
Resolution in computer graphics   22
Luma   23
The unfortunate term "video luminance"   24
Color difference coding   24
Component digital video, 4:2:2   26
Composite video   27
Composite digital video, 4fSC    28
Analog interface   28
High-definition television, HDTV   29

2 Raster images in computing    33

Introduction   34
Symbolic image description   34
Raster images   35
Dithering   38
Conversion among types   39
Data compression   40
Image compression   40
Lossy compression   40

3 Filtering and sampling    43

Introduction   43
Sampling theorem   44
Sampling at exactly 0.5fS    45
Frequency response   48
Frequency response of a boxcar   49
Frequency response of point sampling   50
Fourier transform pairs   51
Digital filters   53
Impulse response   54
Finite impulse response (FIR) filters   54
Physical realizability of a filter   55
Phase response (group delay)   56
Infinite Impulse Response (IIR) filters   57
Lowpass filter   57
Digital filter design   60
Reconstruction   62
Reconstruction close to 0.5fS    62
(sin x)/x correction   63
Further reading   65

4 Image digitization and reconstruction    67

Comb filtering   68
Frequency spectrum of NTSC   69
Spatial frequency domain   72
Image sampling in computing   76
Image reconstruction   76
Spot size   78
Transition samples   79
Picture center and width   79

5 Luminance and lightness    81

Radiance, intensity   82
Luminance   82
Luminance from red, green, and blue   83
Adaptation   85
Lightness sensitivity   85
Lightness, CIE L*    88
Linear and nonlinear processing   89

6 Gamma    91

Gamma in physics   92
The amazing coincidence!   94
Gamma in film   96
Surround effect   99
Gamma in video   100
Rec. 709 transfer function   102
SMPTE 240M transfer function   103
CRT transfer function details   104
Gamma in computer graphics   107
Gamma in video, computer graphics, SGI, and Macintosh   108
Pseudocolor   110
Halftoning   110
Printing   111
Limitations of 8-bit intensity   113
The future of gamma correction   114

7 Color science for video    115

Fundamentals of vision   116
Color specification   117
Color image coding   118
Definitions   119
Spectral power distribution (SPD) and tristimulus   119
Scanner spectral constraints   120
CIE XYZ tristimulus   122
CIE (x, y) chromaticity   125
Color temperature   127
White   129
Perceptually uniform color spaces   130
Additive mixture, RGB    132
Characterization of RGB primaries   133
NTSC primaries (obsolete)   134
EBU primaries   134
SMPTE RP 145 primaries   136
Rec. 709 primaries   136
CMFs and SPDs   136
Gamut   146
Noise due to matrixing   147
Transformations between RGB and CIE XYZ    147
Transforms among RGB systems   148
Camera white reference   149
Monitor white reference   149
Wide gamut reproduction   150
Scanning colored media   150
"Subtractive" mixture, CMY    151
Unwanted absorptions   153
Further reading   154

8 Luma and color differences    155

Color acuity   155
RGB and Y, B-Y, R-Y color cubes   157
Constant luminance   158
Conventional luma/color difference coding   162
Nonlinear Red, Green, Blue (R'G'B')    164
Rec. 601 luma   165
SMPTE 240M luma   166
Rec. 709 luma   166
Errors due to nonconstant luminance   166
Subsampling   168
Luma/color difference summary   168

9 Component video color coding    171

B'-Y', R'-Y' components   172
PBPR components   173
CBCR components   174
Y'CBCR from computer RGB    177
Kodak PhotoYCC   178
Y'UV, Y'IQ confusion   179
UV components   180
IQ components   182
Color coding standards   183

10 Composite NTSC and PAL    185

Subcarrier regeneration   186
Quadrature modulation   187
Decoder and monitor controls   189
Narrowband I chroma   190
Frequency interleaving   191
PAL encoding   192
PAL-M, PAL-N   194
Incoherent subcarrier   194
Analog videotape recording   195
NTSC-4.43   197
SECAM   197

11 Field, frame, line, and sample rates    199

Field rate   199
Line rate   200
Sound subcarrier   200
Addition of composite color   200
NTSC color subcarrier   201
PAL color subcarrier   202
4fSC sampling   203
Common sampling rate   204
Genlock   205

12 525/59.94 scanning and sync    207

Frame rate   207
Interlace   207
Line sync   210
Field/frame sync   211
Sync distribution   213
Picture center, aspect ratio, and blanking   213
Halfline blanking   214

13 525/59.94 component video    215

RGB primary components   215
Nonlinear transfer function   215
Luma, Y'    216
Component digital 4:2:2 interface   216
Component analog R'G'B' interface   217
Component analog Y'PBPR interface, SMPTE   219
Component analog Y'PBPR interface, industry standard    220

14 525/59.94 NTSC composite video    221

Subcarrier   221
Two-frame sequence   222
Burst   222
Color differences, U, V    223
Color difference filtering   223
Chroma, C    223
Setup   224
S-video-525, Y' / C 3.58   225
Composite NTSC encoding   225
Composite digital NTSC interface, 4fSC   226
Composite analog NTSC interface   227

15 625/50 scanning and sync    229

Frame rate   229
Interlace   229
Line sync   232
Field/frame sync   232
Sync distribution   233
Aspect ratio   235

16 625/50 component video    237

RGB primary components   237
Nonlinear transfer function   237
Luma, Y'    238
Component digital 4:2:2 interface   238
Component analog R'G'B' interface   238
Component analogY'PBPR interface   239

17 625/50 PAL composite video    241

Subcarrier   241
Four-frame sequence   241
Burst   242
Color difference components, U, V    242
Color difference filtering   243
Chroma, C    243
S-video-625, Y'/C 4.43   243
Composite PAL encoding   244
Composite digital PAL interface, 4fSC    244
Composite analog PAL interface   245

18 Electrical and mechanical interfaces    247

Analog electrical interface   247
Analog mechanical interface   247
Parallel digital interface   248
Serial digital interface   249
Fiber optic interfaces   250

19 Broadcast standards    251

ITU-R, former CCIR   252
ITU-R scanning nomenclature   252
M/NTSC (NTSC)   253
M/PAL (PAL-M, PAL-525)   253
N/PAL (PAL-N, PAL-3.58)   253
B,G,H,I/PAL (PAL)   254
D,K/SECAM (SECAM)   254
Summary of parameters   254

20 Test signals    257

Colorbars   257
Frequency response   258
Differential gain, DG   258
Differential phase, DP   260
Pulse signals   260
Modulated 12.5T, 20T pulses   262

21 Timecode    265

Introduction   265
Dropframe timecode   266
Longitudinal timecode, LTC   267
Vertical interval timecode, VITC   268
Editing   269
Flag bits   270
Further reading   270

Appendix

A Glossary of video signal terms    273

Index    301

1997-06-23
Charles Poynton - A Technical Introduction to Digital Video