H. Bi et Wy. Chan, RATE-DISTORTION OPTIMIZATION OF HIERARCHICAL DISPLACEMENT-FIELDS, IEEE transactions on circuits and systems for video technology, 8(1), 1998, pp. 18-24
The displacement vector field for motion-compensated coding of image s
equences is represented and coded using a hierarchy of displacement ve
ctor fields over successively finer sampling grids. An efficient metho
d based on the generalized Breiman-Friedman-Olshen-Stone (BFOS) tree-p
runing algorithm is used to find a variable-depth hierarchy that satis
fies a given bit rate or distortion constraint. The variable-depth hie
rarchy corresponds to using a nonuniformly sampled displacement held f
or motion compensation. The proposed scheme is compared with conventio
nal fixed-block-size block-matching motion compensation. The motion in
formation bit rate or the motion-compensation residual energy of the c
onventional scheme serves as the constraint, Simulation results show t
hat the proposed scheme reduces the residual energy by between 0.6-1.5
dB, or the bit rate by 19-54%, while using only 40-100% of the comput
ational complexity of the conventional scheme. The prediction image se
quence produced by the hierarchical scheme offers much better viewing
quality.