Optical Pattern Recognition Experiments of Walsh Spatial Frequency Domain Filtering Method

Abstract

An optical parallel processor for an image recognition system using microoptical devices has been developed. This system expands input images to coefficients of a two-dimensional Walsh spatial frequency domain and discriminates them by performing the inner product to the reference filter. In this paper, we demonstrate parallel optical discrimination of Arabic numerals using this method. First, the mechanism of this recognition method is presented. Next, the reference filter is designed. In order to implement the reference filter by using the microoptical devices, the fabrication problems were solved. Finally, the recognition system is constructed and effects of deformation on the input image are experimentally evaluated.