An optical pattern recognition method which can be applied to a joint transform correlator operative to effect correlation processing between a plurality of reference images and at least a single object image to produce correlation peaks corresponding to the respective reference images. The joint transform correlator is provided with a feedback system effective to regulate the intensity of the respective reference images according to the corresponding correlation peak value so as to noise-shape the correlation peaks to discriminate most-correlated reference images. The pattern recognition method is carried out in the correlator sequentially by first preparing a plurality of initial groups each containing a given number of individual reference images and carrying out the pattern recognition of the object image with respect to each of the initial groups to discriminate each of the most-associated reference images having a maximum correlation coefficient in each initial group. Next, the discriminated most-associated reference images are regrouped into new groups, the number of groups is less than that of the initial groups, and the pattern recognition of the object image with respect to the new groups is again carried out so as to enable next regrouping. Then, the regrouping is repeatedly carried out so as to reduce the number of the groups to thereby form a final group and carrying out the pattern recognition of the object image using the final group of reference images to thereby determine a particular reference image corresponding to the object image.
Optical pattern recognition using multiple reference images