SHAPE FROM SHADING USING LINEAR-APPROXIMATION

In this paper, we present an extremely simple algorithm for shape from shading, which can be implemented in 25 lines of C code. The algorit hm is very fast, taking 0.2 seconds on a Sun SparcStation-1 for a 128 x 128 image, and is purely local and highly parallelizable (parallel i mplementation included). In our approach, we employ a linear approxima tion of the reflectance function, as used by others. However. the main difference is that we first use the discrete approximations for surfa ce normal, p and q, using finite differences, and then linearize the r eflectance function in depth, Z(x, y), instead of p and q. The algorit hm has been tested on several synthetic and real images of both Lamber tian and specular surfaces. and good results have been obtained.