Hybrid order statistic filter and its application to image restoration

We introduce a new nonlinear filter for signal and image restoration, the h ybrid order statistic (HOS) filter. Because it exploits both rank- and spat ial-order information, the HOS realizes the advantages of nonlinear filters in edge preservation and reduction of impulsive noise components while ret aining the ability of the linear filter to suppress Gaussian noise. We show that the HOS filter exhibits improved performance over both the linear Wie ner and the nonlinear L filters in reducing mean-squared error in the prese nce of contaminated Gaussian noise. In many cases it also performs favorabl y compared with the Ll and rank-conditioned rank selection filters. (C) 200 1 Optical Society of America OCIS code: 100.2000.