Colour Appearance Issues in Digital Video, HD/UHD, and D‑cinema

158 Pages·2017·5.82 MB·English

Colour Appearance Issues in Digital
Video, HD/UHD, and D‑cinema
Charles Poynton
B. A., Queen’s University, 1976
Thesis Submitted in Partial Fulfillment of the
Requirements for the Degree of
Doctor of Philosophy
Under Special Arrangements with
Graduate and Postdoctoral Studies and
Faculty of Applied Sciences
© Charles Poynton 2018
Simon Fraser University
Summer 2018
Copyright in this work rests with the author. Please ensure that
reproduction or re-use is done in accordance with relevant copyright
regulations.
Approvals
Charles Poynton Colour Appearance Issues in Digital Video, HD/UHD, and D‑cinema
for the degree of Doctor of Philosophy
Examining committee
Chair: Binay Bhattacharya
Professor, Computing Science
Senior supervisor: Brian Funt
Professor, Computing Science
Supervisor: Mark Drew
Professor, Computing Science
Supervisor: Kathleen Akins
Professor, Philosophy
Examiner: Lyn Bartram
Associate Professor, School of
Interactive Arts and Technology
External examiner: Michael S. Brown
Professor, EECS
York University, Toronto
Date Defended/Approved 2018-07-30
Date of this version 2019-10-04
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Abstract
For many decades, professional digital imaging has faced a dilemma.
On one hand, imaging scientists and engineers – and, within the last
two decades, programmers – have been taught that the goal of imag-
ing technology is the accurate “reproduction” of colour values (most
commonly quantified by luminance, tristimuli, and/or chromaticity) on
a display device. On the other hand, digital imaging craftspeople and
artists have learned to manipulate image data as required to yield the
intended visual result, objective inaccuracy notwithstanding.
These approaches have been at odds owing to a fundamental aspect
of colour vision: Colour appearance depends upon the visual conditions
of a scene or a display (particularly, its absolute illuminance or lumi-
nance), the region surrounding the acquired portion of the scene or the
displayed image, and whether the display is emissive or reflective. The
dependence of perceived colour upon absolute luminance and sur-
round conditions is well known in colour science. In the last 20 years,
these visual effects have been quantified in colour appearance models,
and have been standardized (in CIECAM02). However, these effects,
and colour appearance theory, remain largely unknown to imaging
engineers.
Despite the reluctance of scientists and engineers to abandon
their goal of physical accuracy, appearance effects have, in fact, been
accommodated in commercially important imaging systems. However,
appearance effects have been compensated largely at the level of craft,
not science or engineering. Compensation of appearance effects has
been subject to such confusing nomenclature and such poor documen-
tation that it has remained mostly invisible or mysterious to the scien-
tists and engineers.
This thesis seeks to develop a systematic analysis that bridges visual
psychophysics, colour appearance theory, and the practice of image sig-
nal processing in modern digital imaging systems. I analyze and docu-
ment the colour appearance compensation methods that have evolved
in modern digital imaging, and I link to these methods to modern
psychovisual principles and to colour appearance theory.
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dedicated to
Alexander Johnston
1839 –1896
artist and photographer
Wick, Caithness
Scotland
and
Alexander Johnston
1920 –1989
rangeland ecologist, research scientist, and historian
Lethbridge, Alberta
Canada
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Acknowledgements
Thanks to my supervisor Brian Funt, who waited much longer than he 
anticipated, even taking into account Hofstadter’s Law. 
Thanks to my other two supervisory committee members, Kathleen 
Akins and Mark Drew, for agreeing to participate in what – even at the 
outset – promised to be an unconventional PhD programme. Thanks to 
my examiners for their thoughtful comments. 
Thanks to the faculty members at other institutions who helped in 
various ways: Mark Fairchild, Richard Hornsey, Sabine Susstrunk, and 
為ヶ谷 秀一 (Tamegaya, Hideichi). 
I thank Michael Brill for teaching me, 15 years ago, the vital 
importance of distinguishing absolute and relative luminance, and of 
using the correct letter symbols. And for writing a poem about me. 
I acknowledge four colleagues-turned-friends who offered me 
encouragement in the early stages but sadly are no longer with us; 
I think they would have enjoyed the result: Dick Shoup, Lou Silverstein, 
Jim Whittlesey, and Lance Williams. 
I formulated many of the ideas expressed here while teaching. 
Thanks to my long-time collaborators in that effort: Katrin Richthofer 
and Peter Slansky at HFF Munich; and Dirk Meier, Edmond Laccon, and 
all of the UP.GRADErs at DFFB Berlin. 
Thanks to my personal network of colleague/friend reviewers, who 
provided valuable criticism – some, quite harsh! – and literally hundreds 
of suggestions and corrections, all taking time to help me while 
pursuing their own dreams: Don Craig, Dave LeHoty, Barry Medoff, 
Katherine Frances Nagels, Julia Röstel, Mark Schubin, Jeroen Stessen, 
菅原正幸 (Sugawara, Masayuki), and Louise Temmesfeld. 
Thanks to my friends, who provided companionship, advice, 
encouragement, coffee, and other necessities; especially: Marianne 
Apostolides, Jan Fröhlich, Ken Leese, Paul Mezei, and Jan Skorzewski. 
Thanks to my family members for encouragement, support, and love: 
Quinn, Georgia, and Peg. 
Thanks most of all to Barbara, my partner in life. Now it’s your turn. 
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Contents
List of Figures xiii
List of Tables xv
Acronyms & initialisms xvii
Symbols & notation xxi
1 Background & introduction 1
2 Image acquisition and presentation 5
Entertainment programming 6
Axiom Zero 6
OETF and EOTF 8
EOTF standards 8
Image state 8
Acquisition 10
Consumer origination 10
Consumer electronics (CE) display 10
3 Perceptual uniformity in digital imaging 11
Introduction to perceptual uniformity 11
Luminance 12
Tristimulus values 13
Picture rendering I 13
Visual response 14
Logarithmic approximation 15
Lightness 17
Display characteristics and EOTF 18
Eight-bit pixel components 19
Comparing 2.2- and 2.4-power EOTF with CIE L*    21
Picture rendering II 22
Gamma correction 22
Tristimulus values 24
Modern misconceptions 24
Modern practice in video and HD 26
Modern practice in digital cinema 26
Perceptual quantization (PQ) 28
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Summary 28
4 Lightness mappings for image coding 29
Absolute and relative luminance (L and Y ) 29
Brightness and lightness 30
Contrast 31
Contrast sensitivity 32
Historical survey of lightness mappings 33
Weber-Fechner 33
De Vries and Rose 35
Stevens 36
Unification 37
Practical image encodings 37
Implementing de Vries-Rose 39
Medical imaging 41
FilmStream coding for digital cinema 43
Summary 44
5 Appearance transforms in video/HD/UHD/D‑cinema 45
sRGB coding 46
Colour appearance 46
Highly simplified pipeline 48
Definition of scene-referred 50
Definition of display-referred 50
Scene rendering in HD 51
Chroma compensation 52
Axiom Zero revisited 53
Display rendering 54
Scene rendering in sRGB 55
Composite pipeline 56
Optical-to-optical transfer functions (OOTFs) 57
ACES 58
Summary 59
6 Analysing contrast and brightness controls 61
Introduction 61
History of display signal processing 62
Algorithm 65
Digital driving levels 68
Relationship between signal and lightness 69
Effect of contrast and brightness on contrast and brightness 70
LCDs 72
An alternate interpretation 74
Black level setting 76
Non-entertainment applications 77
Summary 78
7 Analysis of greyscale medical image display 81
DICOM 81
Window and level 82
DICOM GSDF 83
Digital driving levels (DDLs) and display EOTF 85
x CONTENTS