1. A method for extracting a watermark signal contained in a watermarked digital image sequence, having two or more frames, comprising the steps of: a) estimating correspondences between one or more pairs of frames in the watermarked digital image sequence; b) computing a displaced frame difference for one or more frames in the watermarked digital image sequence using the correspondences computed in step a); and c) extracting the watermark signal from one or more displaced frame differences.