Abstract: The invention relates to a method and device for coding successive images. The method comprises defining (600) a search area in a reference image; and computing (602) the cost function of each motion vector candidate. Then, the block to be coded is coded (614) by using the motion vector candidate giving the lowest cost function value. In the computation (602) of the cost function, number-theoretic transform is performed (604, 606) for the block to be coded and for the candidate block; multiplication is performed (608) between the block to be coded and the transformed candidate block; correlation between the block to be coded and the candidate block is formed (610) by performing inverse transform of number-theoretic transform for the result of the multiplication; and the correlation formed is used (612) in the computation of the cost function.