ILLUMINANT DIRECTION AND SHAPE OF A BUMP

An algorithm for recovering illuminant direction from the image data o f a smooth Lambertian surface illuminated with a distant pointwise lig ht source is presented. The algorithm is based on analysis of intensit y distributions around structural elements of the image, such as image regions corresponding to bumps. After recognition of a bump in the im age and estimation of the illuminant direction, the image data are int egrated in order to recover the shape of the surface patch. The shape integration algorithm, which is based on a novel theoretical approach, is used to compute the normal vector field in the bump region without use of any explicitly given initial curve or initial data about the b ump region. The theoretical consideration is illustrated with some res ults achieved on simulated and on realistic images. (C) 1998 Optical S ociety of America.