Very Low Bitrate Coding: Which Way Ahead?

The importance of visual communications has increased tremendously in the last decades. The progress in micro{electronics and computer technology together with the creation of networks operating with various channel capacities is the basis of an infrastructure for a new era of telecommunications. New applications are preparing a revolution in every day's life of our modern society. Emerging applications such as video-conferencing [10], cellular video-telephones [1] and multimedia [5, 6, 1] will have a great impact on nowadays professional life, education and entertainment. A common component in all these applications consists of data exchange in form of image or video, through channels at very low bitrates. The digital representation of the visual information in its canonic form generates a huge amount of data. In order to meet the requirements of the new applications, powerful image sequence compression techniques are needed to drastically reduce the global bit rate and o er new functionalities. An overview of existing approaches to very low bitrate image and video coding can be found in [7]. In this paper, we overview a new concept called dynamic coding which would allow to e ciently reach very low bitrate as well as higher bitrate visual data communication.