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. Copyright © 1985 by The Institute of Electrical and Electronics Engineers, Inc.