A two-pass filter for impulse noise reduction based on edge characteristics

In this paper, a two-pass filter is proposed for removing impulse noise to improve image quality. Due to the fact that the edge is more obvious and detected easily, such characteristics of different edges are used to judge whether the pixel is on an edge. Then, the pixels are not on the edges will be filtered by median filter, and further, the other pixels will be detected to preserve original information and reduce impulse noise. Experimental results show that the proposed method is more effective for impulse noise reduction to improve image quality; especially the corruption ratio above 20%.