通过分析SAR影像的Speckle局部统计特性和现有的空间滤波算法, 提出了一种新的Speckle滤波方法, 该方法以局部相对标准差为主要依据, 采用特殊的滤波窗口邻域划分方法, 自适应地调整窗口尺寸和窗口内的滤波区域。该方法被用于多幅ERS-1/ 2SAR图像去Speckle处理, 并与以往的典型算法进行了比较实验, 取得了令人满意的结果。

SAR images are subject to speckle effects which considerably reduce the detection of useful details within the scenes. Based on the analysis of the local speckle statistic characteristics of SAR image (such as relative standard deviation C_u) and algorithms of spatial filtering, an adaptive speckle filtering method is presented in this paper. Firstly, the special pixel neighborhood model is used in the selection of filtering windows, with which the filtering window is divided into 8 mutually exclusive sub windows and the central pixel is the only repetitions pixel in each sub window. Then, for every window to be filtered, the local relative standard deviation C_i is calculated in all sub windows and used as the criteria to select the sub windows with C i<C_u . Those selected sub windows are merged as a filtering area. Finally, recalculating relative standard deviation C_x within the filtering area and different filter was used according to the difference of C_x . In none of sub windows was selected or C_x is larger than a threshold, the size of window should be reduced. If the size of window is 3 by 3 pixels, the central pixel should be replaced with the average of the nearest four pixels around it. The method was applied to both single-look and multi look ERS 1/2 SAR images. The results show that the presented approach has the advantages both in speckle filtering and the preservation of image details.