Abstract: The use of tradition LOG edge detection algorithm to filter SAR image is sensitive to noise,
in the meanwhile, it also damages partial low intensity edges. To solve this problem, a new edge
detection algorithm is proposed. Firstly, the Gaussian function in the traditional LOG operator is
replaced by Adaptive median filter and bilateral filtering. Secondly, the Laplacian is computed after
the image is smoothed. Finally, the zero-crossing points are extracted as the edge of the image. With in
impulse noise image, experiments results demonstrate that the new method can provide better
de-noising results and preserves edges better at the same time. It also improves the accuracy of edge
detection. Compared with the tradition LOG algorithm, it has a better detection result.

Key words: LOG operator, edge detection, edge preserve, bilateral filter, synthetic aperture radar image