Abstract: Wavelet-domain HMT models the dependencies of multiscale wavelet coefficients through the state probabilities of the wavelet coefficients,whose distribution densities can be approximated by the Gaussian mixture model.The algorithm presented in this paper specifies the prior distribution of the real-world image through wavelet-domain HMT model and converts the restoration problem to an constrained optimization one which can be solved with the conjugate gradient method.Experimental results show that the algorithm properly retrieves various kinds of edges and the PSNR and subjective visual effect of the restored images are improved significantly.

Key words: image restoration, wavelet transform, hidden markov tree model, conjugate gradient method