A NEW APPROACH TO REDUCE THE BLOCKING EFFECT OF TRANSFORM CODING

Transform coding has been successfully used for image compression in many applications. However, it suffers from the artifact known as ''blocking effect'' due to division of subblocks. In this paper, we propose a combined-transform coding (CTC) scheme to reduce this effect and hence achieve better subjective performance. First the proposed CTC scheme was described and its information-theoretic properties were investigated. Then a comparison between the CTC scheme and the DCT-based JPEG system and DWHT scheme was made to demonstrate the performance improvement of the proposed scheme. The advantages of the proposed CTC scheme also include 1): no ringing effect due to no error propagation across the boundary, 2): no additional computation and 3): distortion can be held below a certain threshold.