Hybrid optical–digital pattern recognition

Abstract

This paper describes the design of a hybrid optical–digital image-processing system and the development of methods to perform a statistical analysis of the correlation signals. The optical setup is based on a coherent correlator using binary-coded filters. The digital part is based on a microprocessor image-processing system. Six different algorithms for correlation signal evaluation are investigated. Feature reduction is achieved by multivariate analysis. High classification results have been obtained for alphanumerical patterns even in the presence of noise, rotation, change of scale, and shearing.