Color pattern recognition using multiple phase-shifted reference joint transform correlation

Optical joint transform correlation (JTC) technique has been proposed to be an efficient pattern recognition system. Color pattern recognition techniques utilize color of the target objects as additional feature to the spatial characteristics. A new optical JTC technique is developed for color pattern recognition employing the same reference image but with four different amounts of phase shift. A fringe-adjusted filter is also designed to enhance the discrimination between target and non-target objects. The proposed technique yields a very distinctive correlation output for color target detection. The simple architecture can easily be implemented using optical devices, which will provide a real-time pattern recognition decision. Performance of the proposed technique is investigated using computer simulation involving binary as well as gray images.