| Abstract |
A robust technique to prevent illicit copying of video information notwithstanding the use of image scaling is presented. A watermark is embedded into the video signal (e.g., DVD's content or other video sources) at different scales (i.e., sizes). The watermark is maintained at each scale for a predetermined time duration that is sufficient to allow the detector circuit in a DVD-recorder, DVHS recorder, DVCR, or any other digital format recorder to detect, extract, and process information contained in the watermark. At the end of the predetermined time duration, the watermark is changed to a different scale preferably on a pseudo-random basis to ensure that each one of all the scales in a predetermined scaling range is achieved a predetermined number of times. In this way a particular scale that has the counter effect of restoring the watermark to its original position and size can be identified and used to all the watermark to be detected to thus prevent illicit copying. |