EARLY COMPUTATION OF SHAPE AND REFLECTANCE IN THE VISUAL-SYSTEM

A COMPELLING sense of three-dimensional shape may be conveyed by the p hotograph of an object. Cues such as contour, shading, perspective and occlusion, to name a few, contribute to this percept. Psychophysical experiments suggest that certain aspects of three-dimensional shape ar e computed rapidly and in parallel by the visual system(1-7,15). Here we report that reflectance is also computed rapidly; moreover, it is t he apparent reflectance, rather than brightness or perceptual three-di mensional shape, that is the primary basis for discrimination during t he early stages of visual processing.