A wavelet-based watermark casting scheme and a blind watermark retrieval technique are investigated in this research. An adaptive watermark casting method is developed to first determine significant wavelet subbands and then select a couple of significant wavelet coefficients in these subbands to embed watermarks. A blind watermark retrieval technique that can detect the embedded watermark without the help from the original image is proposed. Experimental results show that the embedded watermark is robust against various signal processing and compression attacks.
Cartoon/map images are synthetic graphics without complicated color and texture variation, which makes the embedding of invisible and robust digital watermarks difficult. In this research, we propose a wavelet-based, thresholdadaptive watermarking scheme (TAWS) which can embed invisible robust watermarks into various kinds of graphical images. TAWS selects significant subbands and inserts watermarks in selected significant coefficients. The inserted watermarks are adaptively scaled by different threshold values to maintain the perceptual integrity of watermarked images and achieve robustness against compression and signal processing attacks. Another major contribution of this work is that the cast watermark is retrieved without the knowledge of the original image. The so-called blind watermark retrieval technique is very useful in managing a large cartoon, trademark and digital map databases. Finally, a company logo that clearly identifies the copyright information can be embedded in cartoon and map images without serious perceptual loss. Experimental results are given to demonstrate the superior performance of TAWS.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.