Abstract: To remove impulse noise, median filter is a valid method which is applied in a wide range of real life. Conventional median filter in denoising images loses the edge information easily while images are denoised. This paper presents an improved edge detection-based median filter algorithm. It first detects edge information of noisy image, and then edge information is saved, and then the original noisy image is denoised with median filter, for the edge information which is preserved before denosing; with a small template to remove the noise, then uses it to replace the edge information which is denoised by median fliter. Finally, through experimental verification, the denoising algorithm can be better in preserving edge information while images are denoised.

Key words: median filter, salt &, pepper noise, denoising