Watermarking with dirty paper codes

Several researchers have begun to view watermarking as communication with side information at the transmitter. Theoretical work on this type of communication suggests it is best to use codes that represent each message with many, alternative codewords. Such codes are referred to here as dirty-paper codes, in reference to Costa´s (1983) article. The present paper describes an experiment in which a correlation-based watermarking system is modified to employ dirty-paper codes. Test results show that, as the number of watermark patterns representing a given message increases from 1 (as in a conventional system) to 1024, the watermark can be embedded with increasing fidelity. This improvement in fidelity allows the use of low-frequency patterns, which are inherently more robust than white noise