Optimization of the Predict Operator in Lifting-based Motion Compensated Temporal Filtering

The motion-compensated temporal filtering is an essential part of a scalable wavelet-based video coding scheme, which applies a temporal wavelet transform in the motion direction over the frames of a video sequence. The lifting structure of the temporal filter bank tackled in this paper involves a predict operator which makes use of two motion vector fields to bidirectionally predict frames from their neighbouring ones. We show in this paper that there exists an optimal algorithm allowing to estimate jointly these two motion vector fields subject to an optimization criterion directly related to the coding of the detail subbands. We provide an iterative suboptimal form of this algorithm implementing this approach. We show that this algorithm provides substantial gains in terms of PSNR, with the same complexity as a separate estimation of the two motion vector fields.