Abstract: Bi-histogram equalization was combined with local enhancement to preserve brightness and improve performance of detail preservation.Since local enhancement is sensitive to noise, the adaptive algorithm was established based on the magnitude of edge pixels that are detected by Canny operator in this paper.The experimental results show that the algorithm, which combining spatial edge information with local gray information, can not only make grayscale of entire image distributed well-proportionally but also enhance local details.Furthermore it can overcome the disturbance of noise effectively.