PURPOSE: To simultaneously use many reference pictures to perform pattern recognition by changing the transmittance or the reflectivity of a part corresponding to each reference picture in linear or nonlinear relations to a correlation coefficient.
CONSTITUTION: A coherent picture to be correlated and a coherent reference picture are simultaneously inputted to a means 4 for obtaining the joint Fourier transform and are subjected to joint Fourier transform, and the result is inputted to a space optical modulator 5, and the intensity distribution picture is displayed on the space optical modulator 5. This intensity distribution picture is read out by the coherent light from a second coherent light source 6 and is subjected to Fourier transform and is converted to a correlation signal by a means 7 which subjects the internsity distribution picture to Fourier transform to convert it to the correlate signal. In such a case, an image projection optical system can be built in as the preprocessing for inputting an input image, and the input intensity of a reference picture 3 having the same space frequency component as a picture 2 to be correlated is relatively increased. Thus, the number of reference pictures to be used at a time is increased.
MITSUOKA YASUYUKI
YOSHIKAWA TOMOHIRO
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