Reduced ordering technique of impulsive noise removal in color images

In the paper a fast technique of impulsive noise removal in color images is described. The proposed method is assigning to pixels of the filtering window the sum of the distances to their k nearest neighbors. The difference between the trimmed sum assigned to the central pixel and to the pixel minimizing the cumulated distances is treated as a measure of pixel's distortion caused by the impulsive noise process. If the difference exceeds a global threshold value, then the central pixel of the processing window is replaced by the mean of the pixels from the window, which were found to be not corrupted, otherwise the central pixel is retained. The new filtering design is able to effectively suppress impulsive noise, while preserving fine image details. The performance comparison shows that the proposed filtering design yields significantly better denoising results than the most efficient filters developed for the impulsive noise suppression in color images.