Interframe image sequence coding using overlapped motion estimation and wavelet lattice quantisation

We present a method for low bit rate video coding based on wavelet lattice vector quantisation. It is shown that the overlapped block matching (OBM) motion compensation increases the efficiency of the wavelet video codec, by eliminating the blocking artefacts in the prediction error image introduced from the conventional block matching. The motion compensated prediction error signal is coded using a method which combines wavelet transform and lattice vector quantisation, referred to as successive approximation wavelet lattice vector quantisation (SAWLVQ). In this technique, the most important (in terms of energy) wavelet coefficients are successively coded by a series of vectors of decreasing magnitudes. The structural similarities among the bands of same orientation are exploited by incorporating a block zero-tree structure. Simulation results demonstrate that this scheme achieves very good performance for low bit rate video coding. Comparison with the standard RM8 model of the H.261 video codec, shows that the OBM-SAWLVQ codec results in improvements in both the peak signal-to-noise ratio performance and the subjective quality of the reconstructed pictures.<
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