Results on deriving optimal filters for illumination-invariant color texture recognition

Color textures contain a large amount of spectral and spatial structure which can be exploited for recognition. Recent work has demonstrated that spatial filters offer a convenient means of extracting illumination-invariant spatial information from a color image. In this paper, we address the problem of designing optimal filters for illumination-invariant color texture discrimination. Color textures are represented by a set of illumination-invariant features that characterize the color distribution of a filtered image region. Given a pair of color textures, we derive a spatial filter that maximizes the distance between these textures in feature space. We provide a method for applying the pair-wise result to obtain a filter that maximizes discriminability among multiple classes. A set of experiments on a database of deterministic and random color textures obtained under different illumination conditions demonstrates the improved discriminatory power achieved by using an optimized filter.