REMOVING SPECULARITIES FROM COLOR IMAGES FOR SHAPE FROM SHADING

Specularly reflecting surfaces confuse traditional shape-from-shading algorithms because the variation in image intensity within a specularity does not directly relate to the cosine of the incident angle, as it would for a simple Lambertian reflector. To overcome this problem, color is introduced and a method of removing the specular component of the intensity variation is proposed based on a dichromatic model of surface reflection. Unlike Shafer’s method for specularity removal, which is restricted to unifonnly colored surface patches, our algorithm uses information from several differently colored regions. The specular component due to interface reflection does not change across the regions even though the diffuse component due to body reflection does. In color space, the regions project to planes and the color of the specular component is found as the common intersection of these planes. Once the color of the specular component is known, it is removed from the original image. The resulting image preserves the relative intensity of the diffuse component so it can then be successfully input to a traditional shape-from-shading algorithm…