Asymmetrical orientation weighted mean filter for salt-and-pepper noise removing
Xiaodong Zhou · Laser & Infrared · 2011
Because a few interferential pixels will be involved in the filter operation when the traditional filter based on symmetrical window is used,image blurring always occurs in traditional image filtering.This paper presents an asymmetrical orientation weighted mean filter to remove the salt-and-pepper noise in the images.Firstly,the noise pixels are detected based on regional gray extreme value.Secondly,a concept of asymmetrical orientation window is proposed based on symmetrical orientation window,and the actual filter window of noise pixel is selected adaptively according to the principle that the filter window has the minimal standard deviation.Then,a weighted mean filter that the weight value is inverse proportional to the distance to the filter pixel is performed in the selected asymmetrical window.Lastly,a secondary confirmation to the noise pixel is carried out for correcting the wrong-checked noise pixel in forward noise detection.The experimental results show that the proposed algorithm outperforms the algorithms based on symmetrical window in aspects of noise removing,preserving of image edge and processing speed.Comparing with the traditional median filter and some improved algorithms,the algorithm proposed in this paper shows superior capability.