  A comparative study of different block matching alternatives for motion
estimation is presented. The study is focused on computational burden and
objective measures on the accuracy of prediction. Together with existing
algorithms several new variations have been tested. An interesting modification
of the conjugate direction method previously related in literature is reported.
This new algorithm shows a good trade-off between computational complexity and
accuracy of motion vector estimation. Computational complexity is evaluated
using a sequence of artificial images designed to incorporate a great variety
of motion vectors. The performance of block matching methods has been measured
in terms of the entropy in the error signal between the motion compensated and
the original frames.
