Optimality of multiple entropy coder systems for nonstationary sources modelled by a mixture distribution

A mixture distribution model is introduced to characterize the source statistics in a frequency domain image coder. More specifically, a Gaussian mixture distribution is shown to be a good statistical model of the probability density function of the composite decomposed signal. Theoretical results based on the mixture distribution model are found that quantify the obtainable entropy rate gain in the coder when using multiple entropy coders. A practical image coder using the theoretical concepts is proposed. The simulation results show close correspondence with the predicted theoretical results, thus, verifying the accuracy of the mixture distribution model