Iteratively Designed Optical Correlation Filters For Distortion Invariant Recognition

Abstract

An iterative method is used to design distortion invariant correlation filters. Target images can be detected, for example, independently of their position, rotation, or scale. Optical correlation filters designed using this technique retain full position invariance. The filter design begins by finding the distortion invariant modes for a particular image. This paper reviews the basic design process for a filter that is position, rotation, and intensity invariant. The emphasis is on determining the practical utility of the proposed methods and demonstrating the filters experimentally. Numerical simulations demonstrate that the proposed method can detect targets that are buried in noise. Computer generated holographic filters are fabricated using an electron beam. Experimental results are in excellent agreement with analytical and numerical computations.