Single and multiple spread spectrum watermarking based on periodic clock changes

This paper analyses a spread spectrum watermarking embedding and decoding scheme based on periodic clock changes (PCC) for digital images. The PCC spreading properties and applications in multiuser communications are recalled. The theoretical and experimental decoding performance of this alternative spread spectrum technique are compared with a classical Direct Sequence (DS) method. PCC proves to be a simple alternative to pseudo-noise modulation spreading methods, that provides similar performance.