Computation of the coding gain for subband coders

A procedure to evaluate the coding gain for 2-D subband systems is explicitly presented, The technique operates in the signal domain and requires the knowledge of the input process auto-correlation function, Both the case of uniform subband and pyramid decomposition are considered. In the case of a separable input process spectrum, the evaluation can be performed by considering appropriately defined 1-D systems, thus, making the procedure very convenient in terms of computational complexity, Using a model that has been recently derived for difference images in motion-compensated image sequence coders, we compare the performance of several filter banks and transform coders in terms of coding gain and asymptotic rate-distortion figures, The results for intraframe and interframe coding show that uniform subband coders can have a performance superior to that of transform coders, Pyramidal schemes appear to have a slightly worse performance.