非等分割サブバンド/ウェーブレット変換符号化における動き補償フレーム間予測の周波数領域実現

概要

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A new type of motion compensated subband coding method suitable for wavelet transform and octave spaced QMF bank is described in this paper. Although the energy compaction of wavelet transform is comparable to Discrete Cosine Transform, wavelet transform does not produce artifacts such as blocking effects and mosquito noises, which are most typical problems in the DCT coding. However, when we combine the intraframe/MC-interframe adaptive prediction and wavelet transform, the problems of 1) level gaps between two successive MC blocks (caused by block matching process), and 2) level gaps between intraframe and interframe blocks should be solved. Because those level gaps contain very high frequency components, they reduce the efficiency of subband codings. Thus, we propose a hybrid coding structure, where motion estimation is carried out in the image domain, and interframe differences are taken in the frequency domain. In this method, interframe prediction and intra/inter switching can be carried out in the frequency domain. Thus, level gap problem does not appear. In addition, we show that the process of loop filtering can be carried out by only discarding high frequency band data of prediction images. Also, an adaptive loop filtering can be performed by varying the number of bands to be used for interframe prediction.
社団法人映像情報メディア学会の論文
1991-11-22