Methods and systems for obtaining a motion vector between two frames of video
image data are disclosed. Specifically, methods and systems of the present invention
may be used to perform a block-matching algorithm over a two-dimensional search
area in a manner that reduces number of comparisons. In particular, the method
determines a best candidate block for each strip based by searching in a first
dimension of a two-dimensional search area and based on a predetermined difference
criterion. The method then determines a second set of best candidate blocks by
performing a limited search in the other direction based on the results from the
search in the first dimension. The method then determines a motion vector for the
best candidate block. Integral projection arrays may be used to further optimize
the search. The methods and systems of the present invention may be used in optimizing
digital video encoders, decoders, and format converters.