Coefficient‐based adaptive transform coding scheme

Abstract

AbstractA coefficient‐based, adaptive, orthogonal transform coding scheme is proposed to enhance the performance of interframe DPCM/orthogonal transform coding which has currently become the mainstream coding method in use for video signals. In this proposed scheme, the widely used block‐based inter‐ and intracoding modes are supplemented by introducing a new coding mode, the “mixed mode,” that has the characteristic of optimally controlling prediction and quantization on an orthogonal transform coefficient basis. Based on a statistical model of the video signal, it is shown that the prediction coefficients and quantizer of the proposed scheme can be theoretically optimized. Results from computer simulations on real images show that in terms of an objective evaluation measure (weighted signal‐to‐noise ratio) that reflects properties of the human visual system, that a performance gain of 4.6 dB over the H.261 standard is obtained and 3.4 dB gain over MPEG is obtained. From the perspective of subjective evaluations, it is shown that it is possible to greatly reduce block noise, of course, in exchange for some resolution degradation from mosquito noise.