YACCD: Yet Another Color Constancy Database

摘要

Different image databases have been developed so far to test algorithms of color constancy. Each of them differs in the image characteristics, according to the features to test. In this paper we present a new image database, created at the University of Milano. Since a database cannot contain all the types of possible images, to limit the number of images it is necessary to make some choices and these choices should be as neutral as possible. E.g. a database whose images always contain a white area is suitable for algorithms based on the White Patch approach; on the contrary, the complete absence of white areas can exploit algorithms with alternative approaches. Thus, the first image detail that we have addressed is the background. Which is the more convenient background for a color constancy test database? This choice can be affected by the goal of the color correction algorithms. In developing this DB we tried to consider a large number of possible approaches considering color constancy in a broader sense. Images under standard illuminants are presented together with particular non-standard light sources. In particular we collect two groups of lamps: a group of characterized neon lamps with a weak color cast, suitable to test the precision of a color correction algorithm and a group of tungsten bulbs with a colored coating and strong color casts, very difficult to remove, suitable to test robustness and efficacy. Another interesting feature is the presence of shadows. The presence of different lightness levels in the same image allows to test the local effects of the color correction algorithms. The proposed DB can be used to test algorithms to recover the corresponding color under standard reference illuminants (e.g. D65), or alternatively assuming a visual appearance approach, to test algorithms for their capability to minimize color variations across the different illuminants, performing in this way a perceptual color constancy. This second approach is used to present preliminary tests. The IDB will be made available on the web.