Deblocking of block-transform compressed images using weighted sums of symmetrically aligned pixels

A new class of related algorithms for deblocking block-transform compressed images and video sequences is proposed in this paper. The algorithms apply weighted sums on pixel quar-tets, which are symmetrically aligned with respect to block boundaries. The basic weights, which are aimed at very low bitrate images, are obtained from a2-Dfunction which obeys prede ned constraints. Using these weights on images compressed at higher bitrates pro-duces a deblocked image which contains blurred false edges near real edges. We refer to this phenomenon as the ghosting e ect. In order to prevent itsoccurrences, the weights of pixels, which belong to non-monotone areas, are modi ed by dividing each pixel's weight by a prede ned factor called a grade. This scheme is referred to as weight adaptation by grad-ing (WABG). Better deblocking of monotone areas is achieved by applying three iterations of the WABG scheme on such areas followed by a fourth iteration which is applied on the rest of the image. We refer to this scheme as deblocking frames of variable size (DFOVS). DFOVS automatically adapts itself to the activity ofeachblock. This new class of algorithms produces very good subjective results and PSNR results which are competitive relative to available state-of-the-art methods