Use of true-complement optical images for efficient associative memory implementation

While true and complement images have the same information content, it is advantageous to retain both kinds of images for associative memory. This allows the implementation of a very simple optical computer which can perform real-time image matching. If a test image and a complementary stored image is compared optically with a complementary test image and a stored image, the emerging light intensity is proportional to the Hamming distance between the images. The suggested architecture then carries out efficient parallel comparison and points out the best matched test image using a TV screen and transparencies. A time-varying light-intensity (or a time-varying thresholding voltage) source and a thresholding device are used to select the best match in parallel. The architecture is also ideally suited to finding the closeness of match of two images for quality control-type operations. It can also be used for providing a feedback to search for the best match