Noise immunity of threshold decomposition optoelectronic order-statistic filtering

Abstract

High-speed analog optoelectronic image processing systems are generally characterized by low accuracy and are not well suited to applications requiring large dynamic range. We show that the low accuracy of a typical analog optoelectronic convolver can be tolerated in a high-accuracy application when threshold decomposition is used to perform order-statistic processing on digitized gray-scale imagery. The robustness of the method in the presence of system noise, combined with the parallelism of the optical convolver, suggests that hybrid analog optical/digital electronic processors for order-statistic image processing may be attractive alternatives to all-electronic processors. We analyze the immunity of such a hybrid processor to noise generated by spatial variations of emitter and photodetector arrays for the order-statistic operations of median filtering, dilation, and erosion.