MOTION COMPENSATION TECHNIQUE FOR SCALED DOWN PICTURES RECONSTRUCTED BY COMPATIBLE CODING SYSTEM : A study on drift problem

Abstract

This report presents a new motion compensation technique for scaling decoder. The decoder applies inverse DCT of different sizes than that of the encoding DCT and scaling motion vectors accordingly, to reconstruct images that have different dimensions than those of the originally coded picture. The scheme based on the problem that the downsampled motion compensation of existing decoders essentially effects a spatial low-pass filter. Then, we improved the spatial frequency response of motion compensation by modifying the half- and quarter-pel filters. Reconstructed image quality is improved, and as a result, propagation of error is also reduced.