SHIFT-INVARIANT OPTICAL ASSOCIATIVE MEMORY - TRIPLE OPTICAL CORRELATOR CONFIGURATION WITH PATTERN PREPROCESSING FOR ENHANCED INTERCLASS DISCRIMINATION

The recognition of incomplete patterns in a triple optical correlator configuration is presented. To provide a higher orthogonality of the i nput patterns, they are preprocessed in the first correlator. Some hig h order spatial differential operators are considered for this attempt . A phase-only filter that matches with the target pattern is introduc ed in the Fourier plane of the second correlator; the cross-correlatio ns of the target with the processed patterns are obtained in the outpu t plane. These signals are used to illuminate the matched filter intro duced in the Fourier plane of the third correlator. If an incomplete v ersion of the target is introduced in the input plane of the system, i t will be reconstructed in the output plane. To avoid the distortion o f the reconstructed image, the cross-correlation signals are nonlinear ly processed before introducing them in the third correlator. The perf ormance of this system is checked by computer simulation experiments. Incomplete versions of the target are introduced in the input plane to gether with some different patterns. Versions of the target, 45% incom pleted, are shown to be recognized among other different patterns. (C) 1996 Society of Photo-Optical Instrumentation Engineers.