Ratio of exponentially weighted average (ROEWA) operator is an multi-edge detector suitable for SAR images. The detector which is unable to compute the edge direction

cannot get the exact edge position. The reasons for these problems are analyzed and the flow chart of edge detection is modified in this paper. The constant false alarm rate (CFAR) character is retained by the traditional operator and the accuracy of non maxima suppression (NMS) is improved by the difference operator. Then Radon transform is carried out to get the edge direction for its excellent geometrical analysis and noise immunity properties

and by this way

the line connection is facilitated. The experiment results based on the SAR images show that the performance of the improved algorithm is robust and efficient.