WAVELET BASED LOW BIT RATE VIDEO CODING USING BLOCK-TREE APPROACH

Wavelet transformed images exhibit both inter- and intra-subband correlations. Most of the wavelet based hybrid video coding techniques exploit only inter-subband correlation through zero-trees. However, in the motion compensated predictive error frames, intra-subband correlation is likely to be dominant. Thus, in order to improve the coding efficiency of the wavelet-based video coders, the coding algorithm should exploit both correlations in an efficient manner. In this paper, we design a hybrid video coder (with temporal motion compensation and 2D wavelet transform) in which wavelet coefficients are coded using a new algorithm, named wavelet block-tree coding (WBTC). The proposed algorithm exploits both inter- and intra-subband correlations through spatial orientation tree of blocks. In addition, the interdependency of three colour planes is efficiently exploited in the proposed coder. Simulation results show that the proposed video coder outperforms other state-of-the-art video coders including H.263+ by approximately 1-2 dB.