Dictionary approximation for matching pursuit video coding

Previously, we demonstrated an efficient video codec based on overcomplete signal decomposition using matching pursuits. Dictionary design is an important issue for this system, and others have shown alternate dictionaries which lead to either coding efficiency improvements or reduced encoder complexity. We introduce for the first time a design methodology which incorporates both coding efficiency and complexity in a systematic way. The key to our new method is an algorithm which takes an arbitrary 2-D dictionary and generates approximations of the dictionary which have fast 2-stage implementations. By varying the quality of the approximation, we can explore a systematic tradeoff between the coding efficiency and complexity of the matching pursuit video encoder. As a practical result, we show cases where complexity is reduced by a factor of 500 to 1000 in exchange for small coding efficiency losses of around 0.1 dB PSNR.