Recovering the shading image under known illumination

Given a standard RGB color image, an approach to recovering the shading image, an intrinsic image that depends only on the geometry of the viewing situation, is presented. The approach is formulated for scenes that exhibit both diffuse and specular properties. It is discriminative in the sense that variations in intensity caused by material changes are first detected and then removed. Material changes are detected using a method based on color information alone. The method stems from a scheme proposed here to handle specularities under known scene illumination chromaticity. This scheme is also used to produce an image that is free of specular reflections. Any material changes are then removed from this specular-free image by using an inpainting technique. The performance of the proposed approach has been tested on synthetic images.