A SCALING INDEPENDENT TECHNIQUE FOR WATERMARKING IMAGES.

摘要

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 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 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 allow the watermark to be detected.