Ordering Threshold Switching Median Filter
Ding Run · 2004
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.