DC coefficient restoration using MAP estimation technique

The DC coefficient restoration scheme is a technique which can be used to increase the compression ability of transform image coding by not transmitting the DC coefficients but estimating them from the transmitted AC component. In the last decade, the minimum edge difference criterion is used in the scheme. However the criterion fails at the locations where the discontinuities are along the block boundaries and therefore results in observable blocking effect around these locations or higher bit rate. We propose a new criterion using the maximum a posterior (MAP) estimation technique which preserves the discontinuities during the DC coefficients restoration and solves the blocking effects in the restored images.