Patent ID: 7203335

Claim:
A method for extracting a watermark signal contained in a watermarked digital image sequence, having two or more frames represented by pixel values, wherein the watermark is extracted without using frames from an original unwatermarked digital image sequence, comprising the steps of: a) estimating pixel correspondences between one or more pairs of frames in the watermarked digital image sequence; b) computing one or more displaced frame differences for one or more frames in the watermarked digital image sequence using the pixel correspondences computed in step a) without reference to the original unwatermarked digital image sequence; wherein step (b) further comprises the steps of: (i) computing, without reference to the original unwatermarked digital image sequence, one or more estimated frames using the pixel correspondence computed in step a), and each estimated frame, which is represented by estimated pixel values, has a corresponding frame in the watermarked digital image sequence; (ii) subtracting estimated pixel values of each estimated frame from pixel values of the corresponding frame of the watermarked digital image sequence to produce the one or more displaced frame differences; and c) extracting the watermark signal from one or more displaced frame differences.