Abstract: Real natural images are often contaminated by various kinds of image noise. Traditional denoising methods are generally designed for only one type of noise, so the denoising effect is not good when dealing with mixed noise. To solve this problem, a fast two-step cross non-local hybrid filtering algorithm is proposed. Firstly, the extremum point of pixel gray level is located. The non local median filter is used to remove salt and pepper noise, and the difference integral image of the image is obtained. And then the improved non mean filter is used to further remove the noise. Finally, the non local median filter is used to further remove the noise. The experimental results show that the proposed algorithm achieves higher measurement index and better visual effect in the case of high intensity mixed noise pollution.

Key words: non-local mean filter, non-local median filter, application of integral image, image denoising; mixed noise removal