We propose a prior probability model in the wavelet coefficient space. The
proposed model implements wavelet coefficient thresholding by full posterio
r inference in a coherent probability model. We introduce a prior probabili
ty model with mixture priors for the wavelet coefficients. The prior includ
es a positive prior probability mass at zero which leads to a posteriori th
resholding and generally to a posteriori shrinkage on the coefficients. We
discuss an efficient posterior simulation scheme to implement inference in
the proposed model. The discussion is focused on the density estimation pro
blem. However, the introduced prior probability model on the wavelet coeffi
cient space and the Markov chain Monte Carlo scheme are general.