Digital watermarking has recently been extended from still images to video content. Further research in this area is strongly motivated by an increasing need from the copyright owners to reliably protect their rights. Because of the large economic stakes, digital watermarking promises to have a great future. New applications are likely to emerge and may combine existing approaches. For example, a watermark can be separated into two parts: one for copyright protection and the other for customer fingerprinting. However many challenges have to be taken up. Robustness has to be considered attentively. There are indeed many nonhostile video processings which might alter the watermark signal. It might not even be possible to be immune against all those attacks and detailed constraints have to be defined according to the targeted application. Since collusion is far more critical in the context of video, it must be seriously considered. Finally the real-time constraint has to be met in many applications. In spite of all those challenges, many algorithms have already been proposed in the literature. It goes from the simple adaptation of a watermarking algorithm for still images to the really video specific watermarking scheme.
Open paths still remain in video watermarking. This technology is indeed in its infancy and is far from being as mature as for still images. Quite all possible image processings have been investigated for still images watermarking. On their side, the proposed algorithms for video have remained relatively simple. Many video processings have not been tried and the line is consequently not exhausted. Moreover, introduction of perceptual measures has significantly improved the performances of algorithms for still images. This approach has not been fully extended to video yet. Perceptual measures for video exist but the major challenge consists in being able to exploit them in real-time. Finally, the second generation of watermarking algorithms has only given its first results. Future discoveries in this domain are likely to be of great help for digital video watermarking.