Analysis of Non Linear Filters with Various Density of Impulse Noise for Different Window Size

Corrupted digital images are recovered by using median filters. The most frequently occur noise is salt and pepper type impulse noise. As the noise increases it becomes hard to recover the noisy digital image. Different median filters have been suggested to recover it. Size of the window taken in the filter is also the important factor at different level of noises. The performance of standard median filter (SMF), centered weighted median (CWM) filter and directional weighted median (DWM) filter is tested on gray scale images corrupted with variable percentage of salt & pepper noise impulse noise. It is also tested for different window sizes of filters. Some filter performs better at low noise while some performs better at high noise. At higher level of noise, large window size in the filters works better than small window size. These comparisons are very helpful in deciding the best filter at different level of noise.