说明：  斑点抑制各向异性扩散滤波（SRAD）算法。滤波的目的有两个：一是抽出对象的特征作为图像识别的特征模式；另一个是为适应图像处理的要求，消除图像数字化时所混入的噪声。
(Speckle suppression anisotropic diffusion filter (SRAD) algorithm. There are two purposes of filtering: one is the feature of the extracted object as the feature pattern of image recognition, and the other is to eliminate the noise mixed when the image is digitized to meet the requirements of the image processing.)