Novel robust rank KNN filters with impulse noise suppression for image processing

Novel robust filtering algorithms applicable to image processing are introduced. They were derived using robust M-type point estimators and the restriction technique of the well-known KNN filter. The derived filters effectively remove impulse noise and preserve edge and fine details. The proposed filters provide excellent visual quality of the processed simulated images and good quantitative quality in the MSE sense in comparison to the standard median filter. Recommendations to obtain best processing results by proper selection of derived filter parameters are given. Two derived filters are suitable for impulse noise reduction in any image processing applications. One can use the RM-KNN filters at the first stage of image enhancement followed by any detail-preserving techniques such as the Sigma filter at the second stage.