提出了一种基于排序阈值的开关中值滤波方法以克服图像滤波中去噪与细节保护的矛盾。该方法利用滤波窗口内像素点的排序信息，在极值中值滤波方法的基础上，将受脉冲噪声污染图像中的像素点进一步分为噪声点、边缘细节区和平坦区3种类型。通过对多种图像测试的统计结果，获得合适的分类器参数，然后利用类型判决，进行开关中值滤波，即对噪声点和平坦区进行中值滤波以得到良好的噪声滤除效果，而对边缘细节区不做处理以获得良好的细节保护效果。比较了标准中值滤波、极值中值滤波和本方法的结果。实验结果表明，本方法具有更好的效果。

This paper presents an ordering threshold switching median filter to solve the contradiction between noise attenuation and image detail preserving. From the ordering information of the pixels in the window, and based on extremum median filtering the image corrupted by impulse noise is divided into three pixel classes, that is, noise pixels, edges and details, and smooth regions. With the statistic of a lot of standard images tested, the parameters of the classifier are properly chosen in order to deal with most images adaptively. Then switching median filtering is applied with the classifier. Therefore the smooth regions and noise pixels are filtered by median filters that have a good noise removing capability, especially with the 'salt and pepper' noise. However, most of the edges and details of the image are untouched, so that the restored image can keep details even in variable magnitude impulse noise conditions. A comparison of median filter, extremum median filter and the method in this paper is provided both in subjective images and objective MAE and MSE data. Obviously, the results indicated that the new method has better properties.