Median-type filters with model-based preselection masks

To remove impulsive noise, several variants of median-type filters are presented. They use some prior information provided by the probabilistic composition model of the class of the image being processed. This information is doubly applied; first, in elaborating a noise-estimation mask for the preselection of the pixels which must be filtered; and second, in the filtering process itself. The aim is to avoid the side-effect damage that median-type filters produce in processing the noncontaminated pixels. Experimental results are better than in the conventional median filter.