5. The method of claim 4 wherein said signature and said parametized signals each comprise a plurality of digital words, each digital word of said signature and said parametized signals being derived by comparing the average luminances of selected areas of a frame of said segment to the average luminance of at least one reference area, each of said selected areas providing a bit of said digital word.
5. The method of claim 4 wherein said signature and said parametized signals each comprise a plurality of digital words, each digital word of said signature and said parametized signals being derived by comparing the average luminances of selected areas of a frame of said segment to the average luminance of at least one reference area, each of said selected areas providing a bit of said digital word. 6. The method of claim 5 wherein said selected areas are asymmetrically spaced about the center of said frame.