Pre- and Post-Filtering for Block-Based Image and Video Communication Systems

本研究涉及在基于块的图像/视频通信系统中沿数据块边界进行前后滤波的集成框架的研究和开发。这种新的编码框架可以被认为是对传统的块DCT编码方法的推广，并对其进行了显著的改进。该研究特别针对无线手持设备中资源受限、速度关键和实时应用中的低复杂度图像/视频编码和通信算法或系统进行研究，有望对实际的信号处理、编码和通信系统产生重大影响。通过考虑块间空间相关性和基于局部信号内容动态地自适应算子，大大提高了编码效率。在解码端，提高了感知重建的质量。块伪影通过沿块边界的积极后滤波来减轻，而振铃伪影则通过自适应地改变算子大小而大大减少。通过在空间上扩展信息以及通过基于通信环境和接收的相邻数据动态切换内插后置滤波器，还提高了在噪声信道环境中的稳健性和数据恢复能力。最后，在实用方面，小型本地运算符非常适合并行计算和快速、VLSI友好的、可能无乘法器的实现。现有的基于块的基础设施可以保持不变，因为前/后处理在空间域之外运行。研究人员探索了前/后处理操作员，这些操作员可以与目前在网络和存档数字图书馆中可获得的大量JPEG和MPEG位流保持兼容性。

This research involves the study and development of an integrated framework of pre- and post-filtering along the data block boundaries in block-based image/video communication systems. The novel framework can be thought of as a generalization of and provides a significant improvement for the traditional block DCT coding approach in JPEG and MPEG. The investigation is particularly geared toward low-complexity image/video coding and communication algorithms or systems in resource-constrained, speed-critical, and real-time applications for wireless hand-held devices.The research is expected to have a significant impact on practical signal processing, coding and communication systems. Coding efficiency is greatly improved by taking into account inter-block spatial correlation and by adapting operators dynamically based on local signal contents. At the decoder, perceptual reconstruction quality is enhanced. Blocking artifacts are mitigated with aggressive post-filtering along the block boundaries whereas ringing artifacts are greatly reduced by adaptively varying the operator size. Robustness and data recovery capability in noisy channel environments are also improved by spreading information spatially and by dynamically switching interpolative post-filters based on the communicating environment and the neighboring data received. Finally, on the practical aspect, small local operators lend themselves nicely to parallel computing, and fast, VLSI-friendly, possibly multiplierless, implementations. Existing block-based infrastructure can be kept intact since pre-/post-processing operates outside in the spatial domain. The investigator explores pre-/post-processing operators that can maintain compatibility with the huge collection of JPEG and MPEG bit-streams currently available on the web and in archiving digital libraries.-------------------Level of Effort Statement:At the recommended level of support, the PI will make every attempt to meet the original scope and level of effort of the project.