Post-processing technique based on POCS for visual enhancement in HDTV images

In this paper, we propose a postprocessing technique based on the theory of projection on convex sets(POCS) to reduce the blocking artifacts in HDTV decoded images. In BDCT of HDTV, the image is divided into a grid of non-overlapped 8 × 8 blocks, and then each block is coded separately. A block which is located one pixel apart from the grid of BDCT will include the boundary of the original 8 × 8 block. If the blocking artifact is introduced along the block boundary, this block will have different frequency characteristic from that of the original block. Thus, a comparison of frequency characteristics of these two overlapping blocks can detect the undesired high-frequency components mainly caused by the blocking artifact. By eliminating these undesired high-frequency components adaptively, robust smoothing projection operator can be obtained. Simulation results with real image sequences indicate that the proposed method performs better than conventional algorithms.