An Effective Detail Preserving Filter for Impulse Noise Removal

Impulsive noise appears as a sprinkle of dark and bright spots. Linear filters fail to suppress impulsive noise. Thus, non-linear filters have been proposed. The median filter works on all image pixels and thus destroys fine details. Alternatively, the peak-and-valley filter identifies noisy pixels and then replaces their values with the minimum or maximum value of their neighbors depending on the noise (dark or bright). Its main disadvantage is that the estimated value is unrealistic. In this work, a variation of the peak-and-valley filter based on a recursive minimum-maximum method is proposed. This method preserves constant and edge areas even under high impulse noise probability and outperforms both the peak-and-valley and the median filters.