A new method for optical pattern recognition by correlation measurements

The method of computing correlation functions using a coherent optical analogue computer is well known. In this letter we describe a new method for the recognition of binary patterns. Usually the peak of maximum intensity in the correlation plane is taken as a “measure of similarity”. Instead of this “measure of similarity” we introduce a “measure of distance”. By the method proposed here the pattern to be recognized is detected by a zero in the intensity distribution in the correlation plane.