1. An automated, computerized method for processing an image, comprising the steps of: providing an image file depicting an image, in a computer memory; identifying shadow edges in the image, the shadow edges being identified in an illumination image generated from the image by an optimized solution to an [A][x]=[b] matrix equation wherein [A] expresses values of 0's, 1's and −1's, determined by a constraining relationship derived from same material information, [b] expresses recorded information for the image, and [x] expresses an unknown illumination component of the image; computing gradient information for the image; and modifying the gradient information relative to the shadow edges for improved performance of computer functionality in an image processing operation.