1. A method of selecting, for each of a series of blocks of pixels in a first image, a respective similar block of pixels of a second image, the method including for a current one of said blocks of the first image selecting between a plurality of candidate locations in the second image according to the respective values for each candidate location of a cost function which comprises: (A) a similarity measure between the current block of pixels in the first image and a block of pixels at the candidate location in the second image, and (B) a function of a candidate motion-vector corresponding to the candidate location, a predicted-motion-vector associated with the current block, and a future predicted motion vector of at least one block of the image which is later in the series of blocks than the current block.