1. A computer generated method comprising: a processor performing an exact comparison between a first bitmap and a second bitmap; the processor calculating a number of miscompared pixels that occurred during the comparison; and the processor calculating a quantity value representing a characteristic of the miscompared pixels, wherein the quantity value=Σnr 2 , where n is the number of miscompared pixels in each bin and r is a radius measured as a distance from a center of the miscompared pixels.