Digital watermarking is an effective method for the copyright protection
of multimedia data. In this talk, the definition and characteristics of
watermarking are given and the basic structure model of DCT based
watermarking is introduced. After analyzing the application of spread
spectrum technique in watermarking, we propose an image watermarking
algorithm based on CDMA technique. We also propose a video watermarking
algorithm in uncompressed domain. Blind extraction of watermark is
achieved through the close correlations between neighboring frames.