A flexible structure for fully scalable motion-compensated 3-D DWT with emphasis on the impact of spatial scalability

Abstract

We investigate the implications of the conventional "t+2-D" motion-compensated (MC) three-dimensional (3-D) discrete wavelet/subband transform structure for spatial scalability and propose a novel flexible structure for fully scalable video compression. In this structure, any number of levels of "pretemporal" spatial wavelet decomposition are performed on the original full resolution frames, followed by MC temporal decomposition of the subbands within each spatial resolution level. Further levels of "posttemporal" spatial decomposition may be performed on the spatiotemporal subbands to provide additional levels of spatial scalability and energy compaction. This structure allows us to trade energy compaction against the potential for artifacts at reduced spatial resolutions. More importantly, the structure permits extensive study of the interaction between spatial aliasing, scalability and energy compaction. We show that where the motion model fails, the "t+2-D" structure inevitably produces misaligned spatial aliasing artifacts in reduced resolution sequences. These artifacts can be removed by using pretemporal spatial decomposition. On the other hand, we also show that the "t+2-D" structure necessarily maximizes compression efficiency. We propose different schemes to minimize the loss of compression efficiency associated with pretemporal spatial decomposition.

Modeling Motion for Spatial Scalability

“…Concurrently and independently from our work, similar solutions appeared in the form of "2D+t+2D" schemes [7] and "In-Scale" MCTF schemes [14]. In "2D+t+2D" schemes, several levels of the so-called "pre-S" spatial DWT decomposition precede the subband-independent temporal filtering stage (Fig.…”

“…2). Two major factors contributing to such poor performance of the "t+2D" structure are: 1. inappropriate motion modeling that creates visually annoying artifacts, and 2. subband leakage [7,8,9] induced by shift-variance of critically-sampled DWT transforms. In order to analyze the subband-leakage problem of a "t+2D" scheme, we consider equivalent structure (Fig.…”

Bitplane Image Coding With Parallel Coefficient Processing

“…Although other works in the literature [7], [9], [34] determine the context depending on the position of the significance neighbors, the analysis in [35] shows that simple context formation approaches like (1) also achieve competitive coding performance. This approach is employed herein due to its computational simplicity.…”

Stationary Probability Model for Microscopic Parallelism in JPEG2000

“…The proposed strategy is viable for any context-based coding system such as [19]- [23]. For concreteness, the proposed scheme is described and tested within the framework of JPEG2000, without sacrificing any of the advanced features of the standard.…”