1. A method to track persons, comprising the steps of: (a) generating a first set of facial coefficient vectors by: (i) providing a first image containing a plurality of persons; (ii) locating faces of persons in said first image; and (iii) generating a facial coefficient vector for each said face by extracting from said first image coefficients sufficient to locally identify each said face, (b) generating a second set of facial coefficient vectors by: (i) providing a second image containing a plurality of persons; (ii) locating faces of persons in said second image; and (iii) generating a facial coefficient vector for each said face by extracting from said second image coefficients sufficient to locally identify each face, and (c) tracking the persons within said images, said tracking including comparing said first set of facial coefficient vectors to said second set of facial coefficient vectors to determine for each person in said first image if there is a corresponding person in said second image.