Computing minima and maxima of digital images in pipeline image processing systems without hardware comparators

Several commercially available image processing systems do not have comparators in their arithmetic processors. This fact makes the computation of local minima/maxima of digital images or pixel-by-pixel minima/maxima between two or more images seem impossible. This letter describes an efficient technique for computing maxima and minima without the use of a hardware comparator. The procedure requires only table look-up and simple arithmetic operations, and therefore can be efficiently implemented in commercially available pipeline image processors.