全方向增强局域统计自适应滤波器在平滑雷达图象斑点噪声中的应用

合成孔径雷达图象的斑点噪声是由于合成孔径雷达（SAR）发射的相干干涉波产生的，它严重地影响了合成孔径雷达图象的质量和应用。为了更好地平滑噪声，保护边界和纹理信息，本文在分析和实现适应于SAR图象的各种局域自适应滤波器的基础上，实现了一种新的改进的全方向增强的局域自适应滤波器，它是把（2N＋1）＊（2N＋1）的滤波子窗口分成4N个子窗口，根据不同的子窗口中的局域变化系数来进行滤波，结果表明，这种全方向增强的局域自适应滤波器在保护地物的辐射特性和图象的纹理信息以及增强图象的微细节等方面，均比以前的滤波器有较大的提高。

All Direction Enhancement Adaptive Filter and Its Application in Smoothing Speckle Noise of SAR Images

peckle noise, which originates physically from coherent interference of back-scattered electromagnetic radiation from the multiple scattering elements in a ground illumination cell, makes the radiometric and textural aspects less efficient for application of SAR image. In order to average speckle in the homogeneous areas, preserve edges and linear features, many adaptive filters are analyzed in this paper.A new modified adaptive filter-all direction enhancement adaptive filter are developed in which the (2N *2N) sliding window is divided into 4N subwindows, and the filter works according to the local coefficient of variation of the subwindows. The experiment results indicated that the modified filter performs better than the older ones. It reduces speckles and preserve structural features, edges and small details in all directions in the meanwhile.