An analysis of correlation-based watermarking systems

With recent advances in digital technology, it is now easy to copy digital content. As a result, unauthorized copying of content is widespread and copyright protection has become a serious issue. One solution to this problem is electronic watermarking, for which various techniques have been proposed. However, since no method of evaluation of the robustness of electronic watermarking methods has been established, it is difficult to compare various methods. This paper presents an analysis of the correlation-based electronic watermarking method in which a pseudorandom sequence is embedded as a watermark into the transform coefficients of the image and watermarking is detected by correlation. A method of evaluation is also proposed. Based on the proposed method, an electronic watermarking method using discrete wavelet transforms is proposed. Finally, based on the results, methods for improving the performance of the watermarking method are discussed. (C) 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 86(11): 1-12, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.10093.