<title>Motion-compensated wavelet transform coding for color video compression</title>

Abstract

A video compression scheme based on the wavelet representation and multi-resolution motion estimation (MRME) is presented in this paper. The multiresolution/multifrequency nature of the discrete wavelet transform lends itself as an ideal tool for representing images and video signals. Wavelet transform decomposes a video frame into a set of sub-frames with different resolutions corresponding to different frequency bands. These multiresolution frames also provide a representation of the global motion structure of the video signals at different scales. The motion activities for a particular sub-frame in different resolutions are hence highly correlated since they actually specify the same motion structure at different scales. In the MRMC described the Section 4, motion vectors in higher resolution are predicted by the motion vectors in the lower resolution, and are refined at each step. In particular, we propose a variable block-size MRMC scheme in which the size of a block is adapted to its level in the pyramid. This scheme not only considerably reduces the searching and matching time but also provides a meaningful characterization of the intrinsic motion structure. The variable-size MRMC approach also avoids the drawback of the constant-size MRMC in describing small object motion activities. After wavelet decomposition, each scaled wavelet tends to have different statistical properties. An adaptive truncation process similar to [CHEN 84] was implemented and a bit allocation scheme similar to that in the transform coding is examined by adapting to the local variance distribution in each scaled wavelet. Based on the wavelet representation, variable-size MRMC approach and a uniform quantization scheme, four variations of the proposed motion-compensated wavelet video compression system are presented in Section 6. It is shown that the motion-compensated wavelet transform coding approach out-performs the conventional transform coding scheme in terms of the signal-to- noise ratio as well as the subjective performance.© (1991) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.