Dual-wrapped digital watermarking scheme for image copyright protection

Digital watermarking is an effective way to protect the rightful ownership of multimedia contents. In this paper, a two-phase watermarking scheme is proposed, which extracts both the grayscale watermark and the binary one from the protected images to achieve the copyright protection goal. In the first phase, the proposed method utilizes the pixel values of the original image to construct a grayscale watermark image. In the second phase, a binary watermark image can be further retrieved via the just-procured-permuted grayscale watermark from the first phase. Under these circumstances, the proposed technique results in lossless embedding; in other words, the protected images are the same as the original ones. The overall verification procedure does not need the original image. Only those who have the original grayscale watermark and the corresponding secret keys can extract the grayscale and binary watermarks sequentially, which enhances security and robustness of the proposed watermarking system. Experimental results show that the proposed approach satisfies the general requirements of image watermarking and is superior to related methods in terms of transparency and robustness. Moreover, it is easier to be implemented than transform-domain techniques. These flexible features make the proposed method more feasible and practical for copyright protection.