This invention is intended to enable accurate and high-speed pattern recognition even when an object to be identified changes its size, rotating angle or position. The invention comprises: an optical coordinate convertor for displaying at least one reference image including specified marks and at least one input image to be entered on an electrically addressed spatial light modulator 3 for object image and then converting the displayed images from one coordinate system to a desired coordinate system to produce coordinate-converted images by using the coordinate conversion optical filter array 44 and the coordinate conversion lens array 47; and a joint transform correlator for displaying the coordinate-converted intensity distribution images, produced by the optical coordinate convertor, on the coordinate conversion light-addressed spatial light modulator 13, Fourier-transforming the coordinate-converted intensity distribution images into Fourier-transformed intensity distribution images, displaying the Fourier-transformed intensity distribution images on the Fourier transform light-addressed spatial light modulator 105, and Fourier-transforming again the Fourier-transformed intensity distribution image to determine the correlation coefficients of the coordinate-converted reference image and the coordinate-converted input image. With this construction, it is possible to change the reference image and the kind of coordinate conversion easily and quickly. <IMAGE>
An optical pattern recognition apparatus with coordinate conversion function