A certificate-based watermarking scheme for coloured images

In recent years, much of the research energy within the field of digital watermarking has been focused on techniques that depend on a third party, called the Image Certification Authority, to enhance the digital image copyright protection. However, to record the embedding locations of the watermark bits, in the design of most of these schemes, a secret key has to be generated after embedding one watermark into the cover image. As a result, there wind up to be quite some bunches of secret keys for the user to keep if large numbers of watermarked images are involved, which of course means a lot of inconvenience. In this paper, the authors propose a novel watermarking method to solve this problem. Also depending on the Image Certification Authority for copyright protection, the authors' new method makes a difference by providing the user with the power to process masses of digital image watermarking tasks using just one private key. The results of the authors' extensive experiments have proven both the capability of the proposed technique as an efficient management mechanism and the robustness of it against various image processing attacks such as Joint Photographic Experts Group compression, low pass filtering and high pass filtering as well as noise contamination.