Performing optimal bit-allocation with 3D wavelet coding methods is difficult, because energy is not conserved after applying the motion-compensated temporal filtering (MCTF) process and the spatial wavelet transform. The problem has been solved by extending the 2D wavelet coefficients weighting method with the consideration of the complicated pixel connectivity resulting from the lifting-based MCTF process. However, the computation of weighting factors demands much computing time and vast amount of memory. In this paper, we propose a method, which facilitates the property of sparse matrices, to compute the subband weighing factors efficiently. The proposed method is employed for the 5ââ?¬â??3 temporal filter and the 9ââ?¬â??7 temporal filter in the lifting-based MCTF process. Experiments on various video sequences show that the computing time and memory needed for the computation of weighting factors are dramatically reduced by applying the proposed approach.
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