在标准中值滤波的基础上，当处理每一个象素时，判断该象素是否是滤波窗口所覆盖下邻域象素的极大或者极小值。如果是，则采用正常的中值滤波处理该象素；如果不是，则不予处理。-On the basis of the standard median filter, whether the pixel is large or very small values of the filter window which is covered under the neighborhood pixel. If yes, use the normal median filter to process the pixels　If not, then not be processed.