Digital watermarking through CDMA channels using spread spectrum techniques
Tohru Kohda, Yasuo Ookubo, K. Shinokura · 2002
In image transmission systems using spread spectrum (SS) techniques, the main problem is how to transmit an image whose information is huge, efficiently. We have already proposed a color image communication system through code division multiple access (CDMA) channels with spreading sequences of variable-period to transmit YIQ signals. We propose a digital watermarking system where YIQ signal channels and the embedded watermark image channel are separately used. Such a system has two advantages: (1) interception on communications network is prevented; and (2) the copyright of rightful owner of digital images is protected.