Joint transform correlator tolerant to distortions of the object to detect

C.LA MELA; CLAUDIO IEMMI

Porlamar Venezuela

Congreso; RIAO/OPTILAS 2004; 2004

Comité Territorial de Optica

In most pattern recognition processes, a usual problem to be solved consists in recognizing a target independently of distortions originated, for example, by variations in the perspective views.  In this work we combine the inherent advantages of photorefractive joint transform correlators (JTC), such as simple alignment, robustness and high processing speed, with the excellent performance of the constrained phase-only minimum Euclidean distance synthetic discriminant function filters (POMED-SDF´s), giving rise to a distortion-tolerant photorefractive JTC.  We use a liquid crystal display television (LCTV) in the input plane and a BSO crystal in the joint transform plane.  To implement this filter in the JTC, we propose a method, based on a technique that uses only the phase information of the Fourier Transform of the filter as the reference signal. This method avoids the drawback of reduction of space-bandwidth usually present when representations of continue complex functions, such as POMED-SDF´s, need to be carried out.  By employing this technique, we successfully detect the target also for distortions not included in the training set.