Patent ID: 7190811

Claim:
A computer based method for identifying representations of a first object in at least three images including a first, second and third image comprising a collection of pixels, wherein a position of the first object in the at least three images is different, the method comprising: (a) determining a first difference in values between the first image and the second image at a pixel location; (b) assigning a first sign associated with the first difference; (c) repeating steps (a)–(b) for each of a first set of pixel locations in the first image and the second image; (d) determining a second difference in values between the second image and the third image at the pixel location; (e) assigning a second sign associated with the second difference; (f) repeating steps (d)–(e) for each of the first set of pixel locations in the second image and the third image; and (g) identifying the pixel locations where the first sign and the second sign associated with each of the pixel locations have a first pattern.