Novel robust fine detail preserving filter in the image processing

Robust image filter that can provide the preservation of fine details and effective suppression of multiplicative noise is presented. This filter bases on the M (robust maximum likelihood) estimators and R (rank) estimators derived from the statistical theory of rank tests. The filter proposed consists of two stages: at the first stage, to realize the rejection of impulsive noise, we presented the image filter with an adaptive spike detector and M-estimator modified by median estimator to have the ability to remove outliers. The second stage filter, a modified sigma filter, provides the multiplicative noise suppression combined with detail preserving scheme of a Lee filter. Numerical analysis of the simulation results shows that the proposed image filter has good preservation of fine details, effective multiplicative noise suppression and impulsive noise removal for different type of images in the sense of small detail percentage.