The Colour Image Processing Handbook

The Colour Image Processing Handbook

Edited by

S. J. Sangwine and R. E. N. Horne Department of Engineering University of Reading UK

I ~ 1] I SPRlNGER-SCIENCE+BUSINESS MEDIA, B.V

First edition 1998

© 1998 Springer Science+Business Media Dordrecht Originally published by Chapman & Hali in 1998 Softcover reprint ofthe hardcover lst edition 1998

ISBN 978-1-4613-7647-7 ISBN 978-1-4615-5779-1 (eBook) DOI 10.1007/978-1-4615-5779-1

'Munsell' ,' Judge' and 'ColorChecker' are registered trademarks of Gretag­Macbeth. (http://www.gretagmacbeth.com/) The names 'NCS' and 'Natural Color System' are used with permission of NCS - Scandinavian Colour Institute. 'ColorSync' is a registered trademark of Apple Computer Inc. (http://www . apple.com) 'Calibrator' is a registered trademark of Barco Graphics. (http://www.barco.com/) 'Fujichrome' is a registered trademark of Fujiphoto Film USA Inc. (http://www.fujifilm . com/) 'Kodachrome Gold' and 'Ektachrome' are registered trademarks of Eastman Kodak Company. (http://www.kodak.com!) 'Genesis' is a trademark of Matro" Electronic Systems Ltd. (http://www . matrox . com!) 'Colour Dimensions' is a trademark of Imperial Chemical Industries. 'TekColor' and 'TekHVC' are trademarks of Tektroni" Inc. 'Pentium' is a trademark of Intel Corporation. 'X Windows' is a trademark of Open Group. (http://www.opengroup.org/tech/desktop/X/) 'Uni,,' is a trademark of AT&T.

All rights reserved. No part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, without the prior written permission of the publishers. Applications for permission should be addressed to the rights manager at the London address of the publisher.

The publisher makes no representation, e"press or implied, with regard to the accuracy of the information contained in this book and cannot accept any legal responsibility or Iiability for any errors or omissions that may be made.

Contents

List of contributors ix

Preface xiii

Acknowledgements xv

1 The present state and the future of colour image processing 1

PART ONE COLOUR

2 Colour vision 7 William McIlhagga 2.1 What is colour? 7 2.2 The visual pathway 9 2.3 Light absorption and trichromacy 11 2.4 Colour appearance and opponent processes 16 2.5 Other phenomena 20 2.6 The uses of colour 23

3 Colour science 26 M. Ronnier Luo 3.1 Introduction 26 3.2 The CIE system 27 3.3 Colour measurement instruments 40 3.4 Uniform colour spaces and colour difference formulas 44 3.5 Colour appearance modelling 52

4 Colour spaces 67 H enryk Palus 4.1 Basic RGB colour space 67 4.2 XYZ colour space 69 4.3 Television colour spaces 71

vi Contents

4.4 Opponent colour space 4.5 Ohta hhh colour space 4.6 IHS and related perceptual colour spaces 4.7 Perceptually uniform colour spaces 4.8 Munsell colour system 4.9 Kodak PhotoYCC colour space 4.10 Summary of colour space properties

PART TWO IMAGE ACQUISITION

5 Colour video systems and signals Robin E. N. Horne 5.1 Video communication 5.2 Colour reproduction 5.3 Encoded-colour systems

6 Image sources Christine Connolly 6.1 Overview of sources for image processing 6.2 Cameras

7 Practical system considerations Christine Connolly and Henryk Palus 7.1 Image acquisition technique 7.2 Image storage 7.3 Colorimetric calibration of acquisition hardware

PART THREE PROCESSING

8 Noise removal and contrast enhancement John M. Gauch 8.1 Noise removal 8.2 Contrast enhancement

9 Segmentation and edge detection John M. Gauch 9.1 Pixel-based segmentation 9.2 Region-based segmentation 9.3 Edge detection and boundary tracking

73 75 76 82 86 87 89

93

93 102 108

115

115 116

129

129 137 140

149

150 157

163

164 169 176

Contents vii

9.4 Segmentation and edge detection quality metrics 186

10 Vector filtering 188 Konstantinos N. Plataniotis and Anastasios N. Venetsanopoulos 10.1 The Vector Median Filter 190 10.2 Vector Directional Filters 193 10.3 Adaptive vector processing filters 197 10.4 Application to colour images 205

11 Morphological operations 210 Mary L. Comer and Edward J. Delp 11.1 Mathematical morphology 211 11.2 Colour morphology 213 11.3 Multiscale image analysis 220 11.4 Image enhancement 224

12 Frequency domain methods 228 Stephen J. Sangwine and Amy L. Thornton 12.1 Review of the 2D discrete Fourier transform 230 12.2 Complex chromaticity 231 12.3 The quatemion Fourier transform 235 12.4 Discussion 240

13 Compression 242 Marek Domanski and Maciej Bartkowiak 13.1 Image and video compression 242 13.2 Component-wise still image compression 251 13.3 Exploitation of mutual colour component dependencies 272 13.4 Colour video compression 297

PART FOUR APPLICATIONS

14 Colour management for the textile industry Peter A. Rhodes 14.1 Overview of colour flow in the textile industry 14.2 Colour management systems 14.3 CRT characterization 14.4 WYSIWYG colour management 14.5 Colour notation

307

308 309 313 316 319

viii Contents

14.6 Colour quality control 14.7 The ColourTalk system

326 328

15 Colour management for the graphic arts 332 Jan Morovic 15.1 Overview of the graphic arts environment 333 15.2 Colour management systems overview 334 15.3 Characterization and calibration of system components 335 15.4 Gamut mapping 346 15.5 Current colour management systems 354

16 Medical imaging case study 358 Bryan F. Jones and Peter Plassmatln 16.1 Wound metrics - the background and motivation 359 16.2 Principle of structured light 361 16.3 Implementation and precision of MAVIS 365 16.4 Assessment of the status of healing 369 16.5 Automatic segmentation of the wound 372 16.6 Visualization and storage of data 375

17 Industrial colour inspection case studies 377 Christine Connolly 17.1 Inspection of printed card 378 17.2 Inspection of fast-moving beverage cans 380

References 385

Index 425

List of contributors

Madej Bartkowiak is finishing his PhD in the Institute of Electronics and Telecommunications at Poznan University of Technology, Poland. His pub­lished work to date is in the fields of colour image processing and image data compression.

Dr Mary L. Comer is currently working in the Corporate Innovation and Re­search Department at Thomson Consumer Electronics, Indianapolis, Indiana, USA, where she is involved in the development of digital video products.

Dr Christine Connolly formerly of the School of Engineering at the Univer­sity of Huddersfield, is a Director of Colour Valid Ltd., Bradford, West York­shire, UK. Her current work is in the area of non-contact colour inspection for a range of industrial applications.

Dr Edward J. Delp is Professor of Electrical Engineering in the School of Electrical Engineering at Purdue University, West Lafayette, Indiana, USA.

His research interests include image and video compression, medical imag­ing, parallel processing, multimedia systems, ill-posed inverse problems in computational vision, nonlinear filtering using mathematical morphology, communication and information theory. He has consulted for various com­panies and government agencies in the areas of signal and image processing, robot vision, pattern recognition, and secure communications and has pub­lished and presented over 170 papers.

Dr Marek Domanski is Professor of Image Processing and Multidimensional Systems in the Institute of Electronics and Telecommunications at Poznan University of Technology, Poland. His research activities include multidi­mensional digital filters (linear and nonlinear), passive digital systems, image and video compression, subband coding, image enhancement and restoration. He was a visiting scientist at the University of Ruhr, Bochum, Germany in 1986-1987 and 1990-1991. He has published and presented about 100 pa­pers.

Dr John M. Gauch is an Associate Professor in the Department of Electrical Engineering and Computer Science at the University of Kansas, USA, where

x List of contributors

he has developed a comprehensive system of image processing libraries to support teaching and computer vision research programmes.

Robin E. N. Horne has been a Senior Scientific Officer in the Department of Engineering at the University of Reading, UK since 1981. His technical interests are in video engineering and image processing and he has lectured on these subjects at undergraduate and postgraduate level since 1983.

Professor Bryan F. Jones of the Department of Computer Studies at the Uni­versity of Glamorgan, UK, has worked since 1985 on medical imaging. His particular current field of interest is the measurement and analysis of wounds.

Dr M. Ronnier Luo is a Professor of Colour Science in the Colour and Imag­ing Institute at the University of Derby, UK. He has more than a decade of experience in applying the theories of colour science to industrial problems and is a member of numerous technical committees of the CIE. In addition, he is currently the chairman of the UK'S Colour Measurement Committee (CMC) and was awarded the prestigious Bartleson Award for his contribution to colour science.

Dr William Mc/lhagga has an MSc in mathematics and a PhD in vision sci­ence from the Australian National University. He is currently working on models for detection and discrimination of visual stimuli, and MRI investi­gations of visual operations at The Psychological Laboratory, Copenhagen University, Denmark.

Jan Morovic is currently working towards a PhD in the Colour and Imaging Institute at the University of Derby, UK. He is developing a universal gamut mapping algorithm.

Dr Henryk Palus is a Lecturer in the Department of Automatic Control at the Silesian University of Technology, Gliwice, Poland. He has an extensive research background in the areas of shape analysis, sensor systems, robot vi­sion systems, neural networks, stereovision systems, knowledge-based vision systems and colour computer vision. He was awarded the DAAD Scholarship in 1992 (University of Magdeburg and Technical College Ulm) and a British Council Scholarship in 1995 (The University of Reading). Dr Palus is an Advisory Editor of Machine Graphics and Vision and charter-member of the Polish Association of Image Processing (IAPR member).

xi

Peter Plassmann is a Research Fellow in the Department of Computer Stud­ies at the University of Glamorgan, UK. He is an electrical engineer with research interests in the fields of medical computing and image processing, with emphasis on thermal and 3D imaging of wounds.

Dr Konstantinos N. Plataniotis of the Department of Math, Physics & Com­puter Science, School of Computer Science, Ryerson Polytechnic Univer­sity, Toronto, Canada, specializes in colour image processing, multimedia, content-based retrieval, adaptive systems and fuzzy logic.

Dr Peter A. Rhodes is a Research Fellow in the Colour and Imaging Insti­tute at the University of Derby, UK. His research interests include computer­mediated colour fidelity and communication for which he received his PhD in 1995 from Loughborough University, UK.

Dr Stephen J. Sangwine is an electronics engineer and has been a Lecturer in the Department of Engineering at The University of Reading, UK since 1985. His technical interests include digital circuits and fault diagnosis, a field in which he obtained his PhD in 1991, but since 1992, his research has been in colour image processing with a particular interest in frequency domain techniques.

Amy L. Thornton is a design engineer working on both hardware and software for FFT processing. Following on from postgraduate research for a PhD at The University of Reading, UK, her area of interest is in processing data in the frequency domain.

Professor Anastasios N. Venetsanopoulos is in the Department of Electrical and Computer Engineering at the University of Toronto, Canada. His re­search is in the fields of multimedia, colour image processing, communi­cations, nonlinear and multidimensional signal processing, fuzzy logic and neural networks.

Preface

This book is aimed at those using colour image processing or researching new applications or techniques of colour image processing. It has been clear for some time that there is a need for a text dedicated to colour. We foresee a great increase in the use of colour over the coming years, both in research and in industrial and commercial applications. We are sure this book will prove a useful reference text on the subject for practicing engineers and scientists, for researchers, and for students at doctoral and, perhaps masters, level. It is not intended as an introductory text on image processing, rather it assumes that the reader is already familiar with basic image processing concepts such as image representation in digital form, linear and non-linear filtering, trans­forms, edge detection and segmentation, and so on, and has some experience with using, at the least, monochrome equipment. There are many books cov­ering these topics and some of them are referenced in the text, where appro­priate.

The book covers a restricted, but nevertheless, a very important, subset of image processing concerned with natural colour (that is colour as per­ceived by the human visual system). This is an important field because it shares much technology and basic theory with colour television and video equipment, the market for which is worldwide and very large; and with the growing field of multimedia, including the use of colour images on the Inter­net.

The book is structured into four parts. The first deals with colour princi­ples and is aimed at readers who have very little prior knowledge of colour and colour science. Chapter 2 outlines the theory of human colour vision, because this is what defines colour. Chapter 3 gives an overview of the field of colour science relevant to image processing, and Chapter 4 describes vari­ous possible mathematical spaces or coordinate systems in which colour may be represented, including the equations and coefficients required to convert colour pixel values between different colour spaces. The second part of the book covers colour video technology (Chapter 5), colour image sources and image acquisition (Chapter 6 and Chapter 7). This part is intended to convey the need for care in acquiring images if the results of subsequent processing are to have the best chance of success. As these chapters show, there is much

xiv Preface

more to colour image acquisition than in the case of monochrome. The third part of the book (Chapters 9 to 13) is its core, and covers the main fields of processing so far established, some of them quite mature, others still in the early stages of development. The fourth, and final, part covers some specific applications of colour image processing, including the use of colour in the textile and graphics arts industries, and some industrial and medical applica­tions of colour measurement and analysis.

No book is ever free from errors, and we would welcome comments and corrections, for use in what we hope will be the next edition.

Reading October 1997

S. 1. SANGWINE and

R.E. N. HORNE

Acknowledgements

Thanks are due to Paul Whitlock for help with converting some of the fig­ures to Encapsulated Postscript and for checking and correcting many of the entries in the Bibliography.

The whole book was gathered electronically over the Internet, with the exception of the work of one contributor who became temporarily, we hope, disconnected from the Internet and who submitted material by post on a floppy disk. Without this global infrastructure, our work as editors would have been much harder, and we are grateful to The University of Reading for providing high-quality facilities, chiefly email.

The book was typeset using Jb.T]3X 2£ software. The implementation used was MiKTeX version 1.07 running under Windows '95. Camera-ready copy was produced in 600 dpi Postscript using dvips version 5.66. GSview ver­sion 2.1 proved invaluable in correcting and checking the diagrams and the layout of the text. Our thanks are due to the many authors and contributors who have made their software freely available.