「Illumination Color and Intrinsic Surface Properties--Physics-based Color Analyses from a Single Ima
「Illumination Color and Intrinsic Surface Properties」［論文誌Vol.46, No.SIG9(CVIM11), pp.17 -40(2005)］
In the real world, the color appearances of objects are generally not consistent. It depends principally on two factors: illumination spectral power distribution (illumination color) and intrinsic surface properties. Consequently, to obtain objects' consistent color descriptors, we have to deal with those two factors. The former is commonly referred to as color constancy: a capability to estimate and discount the illumination color, while the latter is identical to the problem of recovering body color from highlights. This recovery is crucial because highlights emitted from opaque inhomogeneous objects can cause the surface colors to be inconsistent with regard to the change of viewing and illuminant directions. We base our color constancy methods on analyzing highlights or specularities emitted from opaque inhomogeneous objects. We have successfully derived a linear correlation between image chromaticity and illumination chromaticity. This linear correlation is clearly described in inverse-intensity chromaticity space, a novel two-dimensional space we introduce. Through this space, we become able to effectively estimate illumination chromaticity (illumination color) from both uniformly colored surfaces and highly textured surfaces in a single integrated framework, thereby making our method significantly advanced over the existing methods. Meanwhile, for separating reflection components, we propose an approach that is based on an iterative framework and a specular-free image. The specular-free image is an image that is free from specularities yet has different body color from the input image. In general, the approach relies principally on image intensity and color. All methods of color constancy and reflection-components separation proposed in this paper are analyzed based on physical phenomena of the real world, making the estimation more accurate, and have strong basics of analysis. In addition, all methods require only a single input image. This is not only practical, but also challenging in term of complexity.
Robby T. Tan 君 Robby T. Tan received the MS and PhD degrees in Computer Science from The University of Tokyo, Japan, in 2001 and 2004 respectively. From May 2004 until April 2005, he was a postdoctoral fellow in Computer Vision (Ikeuchi) Laboratory, and currently he joins National ICT Australia as a research scientist and the Australian National University as an adjunct research fellow. His research interests are in color constancy, intrinsic properties of images, spectral-based analysis and the applications of optics in computer vision.
Katsushi Ikeuchi 君 Katsushi Ikeuchi is a Professor at the Institute of Industrial Science, the University of Tokyo, Tokyo, Japan. He received the Ph.D. degree in Information Engineering from the University of Tokyo, Tokyo, Japan, in 1978. After working at the Artificial Intelligence Laboratory, Massachusetts Institute of Technology for three years, Electrotechnical Laboratory of Japanese Ministry of International Trade and Industry for five years, and the School of Computer Science, Carnegie Mellon University for ten years, he joined the university in 1996. He has received several awards, including the David Marr Prize in computational vision, and IEEE RA K-S Fu memorial best transaction paper award. In addition, in 1992, his paper, "Numerical Shape from Shading and Occluding Boundaries," was selected as one of the most influential papers to have appeared in Artificial Intelligence Journal within the past ten years. He has served as the program/general chairman of several international conferences, including 1995 IEEE-IROS, 1996 IEEE-CVPR, 1999 IEEE-ITSC, 2003 IEEE-ICCV. He is Editor-in-Chief of the International Journal of Computer Vision. He is/was on the editorial board of IEEE Trans PAMI, IEEE Trans RA, Journal of Optical Society of America, and the Journal of Computer Vision, Graphics. He has been a fellow of IEEE since 1998. He is selected as a distinguished lecture of IEEE SP society for the period of 2000-2001, and IEEE CS society for the period of 2004-2006.