Abstract: To filter out salt and pepper noise and Gaussian noise, this paper presents a waveletbased adaptive filtering algorithm for mixed noise. The median filter is firstly applied to remove salt and pepper noise and the edge detection is used to distinguish between the nonedge region and the edge region. Then an improved average filter is adopted on the nonedge region, initially weakening the Gaussian noise, without blurring the edge. Finally, an improved wavelet threshold filtering algorithm is utilized on the entire image, using different threshold functions on different subbands. The parameters of these threshold functions are gained in a linear regression process. The experimental results show that the proposed adaptive mixednoise filtering algorithm can effectively remove salt and