Copyright protection of still images using self-similar chaotic watermarks

Abstract

A spatial domain watermarking algorithm for still images is proposed in this paper. The watermarks are generated by combining scaled versions of 2-D chaotic signals, in order to attain a self-similar structure. In addition, the 2-D chaotic signal generation procedure contains operations which ensure that lowpass watermarks are obtained. Such characteristics (lowpass spectrum, self-similarity) enable robustness against compression, lowpass filtering or, generally, distortions of lowpass nature, as well as, cropping and scaling. An additional advantage of the proposed algorithm is that the detection procedure does not require the original image.