A multiple watermarking algorithm based on CDMA technique

Abstract

This paper proposes a multiple watermarking algorithm based on code division multiple access (CDMA) technique. Before the watermark embedded, each user uses his private key as a seed to generate an address code which is subjected to pseudorandom noise distribution. Each watermark is modulated into a carrier signal with its corresponding address code. And then these carrier signals are added to host media (e.g. image, video and audio). During watermark detection, using the same address code, each user extracts his watermark from the detected media via calculating the correlation coefficient between address code and watermarked vector of the detected media. Each user can embed and extract his watermark independently, regardless of others. The experimental results show that this scheme can embed and extract watermarks independently for each user and is capable for multiple watermarking.