Novel sorter architecture for image processing rank order filters

In this letter a novel sorter architecture for two-dimensional rank order filters is presented. Rank order filters are widely used in image processing applications to smooth noisy images without perturbing edge structures. The main element of such filters is a sorter. In the letter a parallel sorting network is described, based on Batcher´s odd-even merge algorithm. The required chip area of the sorter network is proportional to N(log2N)[(log2 N) + 1], where N is the number of pixels to be sorted. An example of a 25-pixel sorter network is given.