Removal of high density salt and pepper noise using neighborhood based switching filter

A novel fixed 3×3 window based algorithm for the elimination of high density salt and pepper noise is proposed. The proposed method uses a tree based switching mechanism for the replacement of corrupted pixel. The processed pixel is checked for 0 or 255; if found true then the pixel is considered as noisy else termed non noisy and left as unaltered. If the pixel is noisy then it checks for the 4 neighbors of the processed pixel. If all the 4 neighbors are noisy then mean of the 4 neighbors are replaced. If any of the 4 neighbors are not noisy then the corrupted pixel is replaced by unsymmetrical trimmed midpoint. Under high noisy conditions if all the elements of the current processing window is noisy then global mean replaces the corrupted pixel. The proposed algorithm exhibits better performance both quantitatively and qualitatively over the standard and existing algorithms at very high noise densities.