CAREER: Robust Visual Communications for Packet Networks

数字通信的更快的计算速度和更高的可用带宽使得视觉通信日益成为可能——图像和视频的单向和双向交换，包括浏览多媒体数据库、实时成像和视频会议。图像和视频压缩技术的进步促进了可视通信的可行性，分组网络（如今天的ATM和未来的无线ATM网络）可以提供所需的带宽。然而，这些网络不能提供有保证的数据包传输——一些数据可能会丢失。因此，这些网络不能可靠地传递使用当今压缩标准编码的视觉信息。本研究的目标是在不可靠的数据包网络上提供可靠的视觉通信，这些网络具有动态带宽和数据包处理特性，通过专门用于在此类网络上传输的源编码。这项研究涉及开发专门的图像和视频压缩技术，用于在具有动态带宽和分组处理特性的网络上传输。传统上，为了处理传输中的损失，通过源编码将冗余从数据中完全去除，然后通过信道编码重新插入，遵循香农的联合源信道编码定理。本研究研究了冗余源编码，在源编码中加入冗余，使得所需的信道编码更少或不需要，同时比使用联合源信道编码定理获得更好的视觉质量。具体来说，用于子带小波图像表示和视频序列中的时间信息的冗余源编码技术正在开发，以及合适的分组策略。优化的数据划分算法也正在开发中，以允许在具有不同特征的多个子通道上传输。

Faster computing and higher available bandwidths for digital communications have made visual communications increasingly possible - one- and two-way exchange of both images and video, including browsing multimedia databases, real-time imaging, and video-conferencing. Advances in image and video compression have contributed to the feasibility of visual communications, and packet networks such as today's ATM and future wireless ATM networks can offer the required bandwidths. However, these networks cannot offer guaranteed packet delivery - some data can be lost. As such, these networks cannot be used to reliably deliver visual information coded using today's compression standards. The goal of this research is to provide reliable visual communications over unreliable packet networks with dynamic bandwidths and packet handling characteristics through source coding specialized to transmission over such networks. This research involves developing specialized image and video compression techniques for transmission over networks with dynamic bandwidths and packet handling characteristics. Traditionally to deal with loss in transmission, redundancy is completely removed from data via source coding and then reinserted through channel coding, following Shannon's joint source-channel coding theorem. This research investigates redundant source coding, in which redundancy is included in the source coding so that less or no channel coding is required, while achieving better visual quality than if the joint-source channel coding theorem is applied. Specifically, redundant source coding techniques for subband-wavelet image representations and for the temporal information in video sequences are being developed, along with suitable packetization strategies. Optimal data partitioning algorithms are also being developed, to allow transmission over multiple sub-channels with different characteristics.