Mixed noise filtering in digital image

Median filtering algorithm is mainly used to filter salt-and-pepper noise,and mean filtering algorithm is mainly used to filter Gaussian noise.When there are both salt-and-pepper noise and Gaussian noise in digital image,using the two methods separately cannot achieve satisfactory results.A mixed noise filtering algorithm is given in this paper.The algorithm distinguishes salt-andpepper noise and Gaussian noise through setting threshold value at first.Then it filters salt-and-pepper noise with an improved filtering algorithm and then filters Gaussian noise with neighbor domain mean filtering.Simulation results show that this algorithm is simple on calculating and the filtering result is better for mixed noise.