Model-based image coding

Progress in the field of model-based image coding is reviewed, and problems are identified which need to be solved before practical systems can be implemented. Some possible solutions to these problems are suggested, namely (i) improvements in analysis techniques aided by a better understanding of illuminated solid shape, (ii) the hybrid use of traditional techniques such as predictive loops, and (iii) the use of packet networks to accommodate the highly variable bit rate. It is concluded that model-based coding holds the promise of providing transmission of color moving images at between a few hundred bits per second and a few kilobits per second over the PSTN-or more likely over packet networks-at around the end of this century