Region-based wavelet compression for very low bit rate video coding

We present a region-based wavelet compression method for encoding video sequences at very low bit rates suitable for videophone applications. By selectively coding texture information in the regions of interest, we avoid spending bits in the unimportant regions and improve video quality. The embedded zerotree wavelet algorithm is extended to efficiently represent the wavelet coefficients within the regions of interest while exploiting redundancy between subbands. The locations of the regions of interest are selected during the motion estimation process and are transmitted as part of the macroblock type. This technique can provide better quality compared to the new H.263 videophone compression standard. This technique was also incorporated in a more general object-based compression scheme which obtained high scores during the recent MPEG-4 subjective quality evaluations