Practical Joint Transform Correlator System

Pattern recognition technology is of great importance and has found applications in the fields of military target recognition, automation control and finger-print recognition. The purpose of pattern recognition is to analyze, judge and sort the object based on the object characteristics. It can be roughly divided into two categories: the optical pattern recognition and the computer-based digital pattern recognition. The optical pattern recognition has the advantages of being with superior high speed and parallel processing, which makes it a very important way to realize pattern recognition in real- time. However, its disadvantage is of low precision. On the other hand, the digital pattern recognition has the advantages of being with high precision, flexible storage, easy estimation and control, but it has the disadvantages, including mass storage, and the slow speed. Based on the combination of these two methods, a feasible optical-electrical hybrid joint transform correlator is proposed in this paper.First, based upon the spatial matched filter correlation, the joint transform correlation(JTC) is discussed. In order to improve the recognition ability of the classical JTC, the paper describes a technique for modulating and filtering joint power spectrum(JPS).Second, the real-time image's object is ambiguity because of complicated background. It is therefore necessary to pre-process the captured object image and extract its characteristics. In order to solve the distortion problem, including proportional and rotary transformation between the reference and the input image, some useful methods are proposed.Third, a practical optical-electrical hybrid joint transform correlator system is discussed. The system consists of an automatic image-capturing and image-processing unit based on the communication protocol, a high-speed image processing system based on the DSP and a miniature optical-electrical hybrid joint transform correlator.Finally, the experiment system is described and the experimental results are analyzed.