Optical implementation of the Hough transform by a matrix of holograms

The Hough transform is a powerful feature extraction algorithm transforming parametric curves of objects into a smaller feature space called the parameter domain. Optical implementation of the Hough transform by space-variant holographic filters is discussed, and a computer controlled system for generating such filters is described. Employing this system, filters for images of space bandwidth product of 60 × 60 are generated and applied to recognize and detect straight lines and circles in parallel and real time.