The hierarchical motion compensation (HMC) technique has been efficiently used in estimating the real motions for sequential images. Recently, the HMC in the hierarchical structure based on sub-band coding (SBC) has been performed.
In this paper, a new hierarchical block motion estimation technique using SBC is proposed. The original image splits up into 4sub-band signals by use of quadrature mirror filter (QMF). And the 2-dimensional separable low-pass filtered image can be further decomposed into 4sub-band signals, repeatedly. The QMF pyramid is composed of these low-pass filtered images. The general method to estimate the block motions is QMF pyramid is to estimate coarse motion vectors using low spatial frequencies and thereafter refine these motion vectors by use of higher and higher spatial frequencies. In the proposed method, the sub-image in low level pyramid is reconstructed by using 3higher sub-and images of the corresponding low level image. And block motion vectors are hierarchically estimated and the sub-band signals of motion compensated prediction errors are progressively transmitted in this pyramid structure. In order words, the proposed method is to estimate block motions dependent on the transmission band signals.
The simulation results show that the performance of the proposed HMC-SBC scheme is better than those of other conventional schemes in terms of prediction gains and entropies of the motion compensated prediction error frames.
