Copyright Notification and Protection of Multimedia Courseware Based on Dual Digital Watermark

Based on spatial and DCT domains this paper proposes a novel digital watermark solution for the color image of screen stream in multimedia courseware. It embeds visible watermark into spatial domain adaptively, and also embeds invisible watermark encrypted by chaotic sequence into the remained area of the screen color image to achieve protected screencolor image with dual digital watermark embedded. The effectiveness and good results of this method have been testified that the visible watermark is frail to be suitable for copyright notification and the visible watermark has good robustness for copyright protection.