1. One or more computer-readable storage media that store executable instructions to recognize a face, wherein the executable instructions, when executed by a computer, cause the computer to perform acts comprising: detecting, in a first image, a first region that contains a first face; performing a geometric rectification on said first region; performing a photometric rectification on said first region; calculating a plurality of first descriptors of said first image by evaluating overlapping windows of said first image, wherein a descriptor is calculated for each window; comparing said first descriptors to a plurality of second descriptors, said plurality of second descriptors being calculated from windows of a second region of a second image that contains a second face, wherein said comparing produces a plurality of distances comprising a distance for each window location of said first region and said second region; choosing one of said distances to represent a difference between said first face and said second face; and determining, based on said difference, whether said first face and said second face are of a same person.