Maximum video compression using AC-coefficient prediction

The AC-coefficient restoration scheme is a technique used to estimate the AC-coefficients using neighboring DCT block values. In this paper, a new approach has been proposed to increase the compression ratio by estimating the AC-coefficients solely from neighboring DC values. Instead of calculating all the DCT coefficients of a block, only DC values are calculated and transmitted whereas the necessary AC-coefficients are estimated for reference frame reconstruction in the encoder. A similar prediction is done at the decoder with the received DCT-DC values to reduce error accumulation. Using this approach, a high compression ratio is achieved by degrading the image quality to an acceptable level. This method proves to be useful where the bandwidth is critical.