Computational Modeling of Visual Texture Segregation

Visual texture segregation is the perceptual phenomenon illustrated in figure 17.1. In this image a rectangular area composed of small X-shaped patterns appears as a distinct region against a background of L-shaped patterns. This segregation occurs rapidly and unconsciously, without effort or search. The rectangular area composed of Tshaped patterns, however, does not appear as a distinct region in this sense. It is very easy to discriminate among all three pattems, but only the X and L regions display spontaneous segregation. This distinction between pattern discrimination and perceptual segregation gives particular interest to the study of this aspect of visual texture perception. Other aspects of texture perception include the role of texture in the perception of surface orientation and shape and the influence of surface texture in determining color appearance. In this paper we limit consideration to the phenomenon of segregation. Pure texture-based segregation is not a very important phenomenon in everyday visual experience. Objects are not usually distinguished from their backgrounds purely by textural differences. In this respect, the study of pure texture differences (in the absence of differences in brightness, color, depth, or other properties) is analogous to the study of isoluminant color differences, which also are not very common in natural scenes. The relative rarity of isoluminant color discrimination in the real world does not imply that color perception is an unimportant component of seeing. Similarly, the rarity of pure texture differences does not reduce the potential importance of texture perception, especially in the visual processing of complex scenes.