Coefficient color constancy
Coefficient color constancy
复制标题
颜色恒常系数
DOI:
--
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发表时间:
1995
期刊:
影响因子:
--
通讯作者:
G. Finlayson
中科院分区:
文献类型:
--
作者:
B. Funt;G. Finlayson
The goal of color constancy is to take the color responses (for example camera rgb triplets) of surfaces viewed under an unknown illuminant and map them to illuminant independent descriptors. In existing theories this mapping is either a general linear 3 3 matrix or a simple diagonal matrix of scaling coe cients. The general theories have the advantage that the illuminant can be accurately discounted but have the disadvantage that nine parameters must be recovered. Conversely while the coe cient theories have only three unknowns, a diagonal matrix may only partially discount the illuminant. My staring point in this thesis is to generalize the coe cient approach; the goal is to retain its inherent simplicity while at the same time increasing its expressive power. Under the generalized coe cient scheme, I propose that a visual system transforms responses to a new sensor basis before applying the scaling coe cients. I present methods for choosing the best coe cient basis for a variety of statistical models of color responses. These models are rich enough that the generalized coe cient approach su ces for almost all possible sensor sets. To achieve color constancy the correct coe cients must be recovered. Existing algorithms can do so only when strong constraints are satis ed. For example it is often assumed that there is a white re ectance in every scene. In the second part of my thesis, I develop a new coe cient algorithm, which I call color in perspective, based on very weak (and very reasonable) assumptions about the world. I assume only that the range of color responses induced by di erent re ectances varies with a change in illumination and that illumination itself can vary only within certain bounds. I tested the algorithm on real images taken with a color video camera|extremely good iii constancy is delivered. Indeed the degree of constancy compares favorably with the best which is theoretically possible. The methods developed in this thesis can be applied to a variety of other areas including color graphics, color reproduction and color appearance models. iv Acknowledgements My rst and foremost thanks go to my thesis supervisor Dr. Brian V. Funt. He has been exceptionally supportive, directing me to relevant literature in the beginning, providing constructive criticism at every stage and tutoring me in the art of research throughout. On an academic front I have many other people to thank. I am particularly grateful to Dr. Mark Drew with whom I have collaborated on many projects. Dr. Drew has enviable mathematical acumen and he patiently guided me through many mathematical results. Thanks also go to Dr. Binay Bhattacharya for introducing me to computational geometry (a key component of my thesis), Dr. Michael H. Brill for sharing his encyclopedic knowledge of color science with me and to Drs. Ze-Nian Li and Jacques Vaisey for their thesis supervision. For continued trips for tea and co ee: Sanjeev Mahajan (he started it all o ), Sumeet Bawa, Pinaki Mitra, Sheelagh Carpendale and Subho Chatterjee have provided excellent company. On the football (or soccer) pitch thanks go to my fellow Pandemonium team-mates; these include Jacques Vaisey, Petr Kubon, Jean Varaldi, Warren Moors and Tamas \the chief" Erdelyi. For help and support in the lab: Brigitte Dorner, Kobus Barnard and Janet Dueck have been rst class. Partners on numerous and various extra curricular activities include T. Pattabhiraman, Glenn Macdonald and Stephan Wehner. For asking to be acknowledged thanks go to Tammy Laberge. I am especially grateful (again) to three good friends who I have known since arriving in Canada. These comprise Mark Mezofenyi, Allan Bennet-Brown and Gilles Dionne. A nal and heartfelt thanks go to my family all those miles away in Scotland. v Foreword: Thesis Organization Common practice dictates that a thesis should be organized linearly: a smooth progression from introduction, to background, theoretical results, experiments and conclusion. This thesis is not organized in this manner. As such, I feel compelled to comment on the layout of my thesis. Like many bodies of work my thesis encompasses not a single idea but many. While these are all related they are each individually interesting and important. However if I followed common practice I would strip away individual identity in creating the linear whole. Speci cally each section would cover all ideas at the same time. The background section would be the union of background material for the many ideas, the theoretical results the union of derivations, and the experimental results the union of experiments. In this thesis I take a more lateral approach and present each idea by itself. Specifically (excepting the introduction and conclusion) each chapter tackles a single major idea. Only the background, theoretical derivations and experiments relevant to the idea at hand are presented. As such each idea is placed in the context in which it was investigated and each chapter is completely self contained. Moreover, because later chapters build on earlier ones the thesis is still linear though in a di erent (and I would suggest more appropriate) sense. Of course one can argue the merits for either organizational strategy. For example in the linear model de nitions are presented singularly; here they are necessarily duplicated if they are germane to more than one idea. Thus the linear thesis is more compact. However I would contend that the small degree of repetition in lateral theses is worthwhile and constitutes reinforcement of ideas; in essence making things clearer. vi Moreover background material for the subject at hand can always be found locally; there is no need for a tiresome search through earlier chapters. I have to confess that the lateral oragnizational strategy was not my own idea. Rather I was fully prepared to adhere to the strictures of the linear approach until I read the thesis of Lucassen[Luc93]. In reading that thesis I was impressed at the clarity of exposition and this, I feel, was in part due to the separate presentation of ideas. vii
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DOI:
10.1364/josaa.9.001905
发表时间:
1992-11
期刊:
Journal of the Optical Society of America. A, Optics and image science
影响因子:
--
作者:
D. Marimont;B. Wandell
通讯作者:
D. Marimont;B. Wandell
DOI:
10.1364/josaa.3.000029
发表时间:
1986-01-01
影响因子:
1.9
作者:
MALONEY, LT;WANDELL, BA
通讯作者:
WANDELL, BA
DOI:
10.1364/josaa.3.001651
发表时间:
1986-10-01
影响因子:
1.9
作者:
BRAINARD, DH;WANDELL, BA
通讯作者:
WANDELL, BA
DOI:
10.1364/josaa.3.001662
发表时间:
1986-10-01
影响因子:
1.9
作者:
DZMURA, M;LENNIE, P
通讯作者:
LENNIE, P
DOI:
10.1364/josaa.7.000776
发表时间:
1990
期刊:
Journal of the Optical Society of America. A, Optics and image science
影响因子:
--
作者:
Poirson,AB;Wandell,BA
通讯作者:
Wandell,BA