Two-Dimensional Rank-Conditioned Median Filter

A version of 2-D median filter specialized to impulse noise removal introducing negligible distortion in noise-free pixels is proposed. Only pixels of prefixed ranks are replaced with the local median. When extreme ranks (min and mar) are chosen, spikes are selectively suppressed, more efficiently than by median filter. Error probability for salt/pepper noise is theoretically derived. MAE and visual comparisons with median filter attest increased accuracy.