Denoising robust image filter with retention of small-size details in presence of complex noise mixture

In this paper, we present the implementation of the robust detail preserving filters with complex noise suppression for image processing applications. The designed filter is the consequential connection of two filters. The first filter uses the value of central pixel of the filtering window to provide the preservation of fine details and the redescending M-estimators combined with the median estimator to provide impulsive noise rejection. The second filter uses the output of the first filter as the pre-estimator for an adaptive calculation in the redescending M-estimator. We investigated various types of influence functions in the M-estimator those are similar to the ones used in the Sigma filter to provide multiplicative noise suppression. The optimal values of the parameters of designed filters in presence of different noise mixture are determined. Different simulation data are presented in the paper and shown the statistical efficiency of the filters.