Encoding of the chrominance signals in 3D subband-based video coding

Abstract

The authors describe several schemes for the encoding of chrominance signal in the context of color video coding at a total bid rate of 384 kbit/s, based on 3-D spatiotemporal subband decompositions, for teleconferencing applications. The target coding rate is 20 kbit/s per chrominance component. A 14-subband decomposition of the chrominance signals is used throughout. As is the case with the luminance signal, the lowest spatiotemporal subband has the highest perceptual significance; the high-pass temporal subbands contribute to the proper rendition of fast-moving objects; and the low-pass temporal high-pass spatial subbands contribute to the sharpness of the edges of slowly moving objects. Relying on the assumption of perfect correlation between luminance and chrominance signals turns out to introduce smearing artifacts. The final scheme gives a perceptually good colour coder at the very low bit rate of 20 kbit/s per chrominance component which is free of 'shadow artifacts' and edge blurriness. >