A motion vector detection method includes extracting a first block from
the m-th picture, extracting second blocks having a large correlation
with respect to the first block from a (m+n)-th picture ((m+n)>m-th),
detecting first motion vectors between the first and second blocks,
extracting a third block located in spatially the same position as that
of the first block from a (m+i)-th picture ((m+n)>(m+i)>m-th),
computing second motion vectors of (n-1)/n times the first motion
vectors, extracting a fourth block corresponding to a movement position
of the third block from the (m+n)-th picture according to the second
motion vector, and selecting an optimum motion vector maximizing a
correlation between the third and fourth blocks from the first motion
vectors.