A wavelet-based adaptive filtering algorithm for mixed noise is proposed.Firstly

median filter is used in image preprocessing to remove impulse noise.Secondly

the image is conducted two-dimensional wavelet decomposition

obtaining high-frequency and low-frequency sub image.Thirdly

according to the noise distribution of high-frequency sub image

designing new morphological filtering structure elements respectively

then a new threshold discriminant function is defined

adjust parameters is set up separately for high-frequency and lowfrequency sub image

so as to filter out residual noise.Finally

wavelet coefficients were reconstructed.The simulation results show that the algorithm is obviously superior to other filtering methods.