The present invention provides optical pattern recognition apparatus comprising means for generating a coherent image of a joint input image (3) including a plurality of reference images Ri and a signal image S by applying a coherent light beam (1) to the joint input image. Fourier transform means (4) are provided for transforming the coherent image into a joint Fourier transform image, which is then converted by a spatial light modulator (5) into a light intensity distribution. Means (8, 9) are also provided for determining a correlation coefficient between each of the reference images and the signal image based on the light intensity distribution. Feed-back means (2, 11) respond to an output from the correlation coefficient determining means for adjusting the intensity of light applied to the joint input image for generating the coherent image. <IMAGE>
Optical pattern recognition apparatus