SHAPE RECOVERY FROM A COLOR IMAGE FOR NON-LAMBERTIAN SURFACES

A robust method of shape recovery from a color image for non-Lambertia n surfaces is proposed. A new reflectance map for a non-Lambertian sur face is developed so that surface shape can be inferred by use of a sh ape-from-shading technique. A dichromatic reflection model [Color Res. Appl. 10, 210 (1985)] is assumed to describe the color hybrid surface . An extended light source is used so that specular and diffuse reflec tion components can be detected simultaneously in one image. The light source can be an ordinary spherical lamp for domestic lighting. The c olor of the light source is assumed different from that of the object. This is a very mild restriction, which can be satisfied almost always . With the use of color information, regions of an image with hybrid r eflection can be segmented from regions with only diffuse reflection. The conventional reflectance map for a Lambertian surface can be used to recover the shapes of regions with only diffuse reflection. Some re sults based on real experiments and simulations are presented to show the efficiency of our method. (C) 1997 Optical Society of America [S07 40-3232(97)00702-3]