Abstract: Influenced by the uncertain factors such as viewing angle,scale,brightness,stains,vague，images in the acquisition process are usually distorted;subsequently,the image process with be affected.To reduce the distortion and to ensure the precision of edge detection,this paper put forwards  an optimized algorithm of combining median filter with mean filter for edge detection.Simulation results show that this algorithm can effectively suppress noise and improve the precision of image edge extraction.

Key words: median filter, mean filter, edge detection, PSNR, NMSE