Implementation of bipolar real-valued input scenes in a real-time optical correlator: application to color pattern recognition

Preprocessing of the input scene can be used to improve the performance of an optical correlator. The result of the preprocessing algorithms can be bipolar real-valued images, with positive and negative values, for input to the optical correlator. We present different procedures for the implementation of the bipolar real-valued signal with spatial light modulators that work in either amplitude-only or phase-only regimes. We apply these techniques to the implementation of bipolar real-valued preprocessed input images in color pattern recognition. (C) 1998 Society of Photo-Optical Instrumentation Engineers. [S0091-3286(98)00701-6].