HVS-Based Removable Visible Image Watermarking Technique

Along with the development of the multimedia and computer network technique, the storage, copy and transmission of the digital information is becoming easier and easier. This creates a convenient platform to pirate the digital media, thus threatening the legal interest of its originator or owner. As a result, copyright protection of the digital multimedia is a pressing issue which needs to be addressed. Digital water-marking is considered as a promising solution to the afore-mentioned problems and has been a hot research filed in the recent years.Compared with invisible watermarking, visible watermarking the advantage that it does not require special tool or software to extract the embedded watermark, as the visible watermark informs us of the copyright information in a visible manner. In some circumstances, the visible is needed to be removed in order to approximately or losslessly recover the original signal. This highlights the need for removable visible watermarking techniques. As a new research filed, removable visible watermarking has attracted the attention of a number of scholars, but only a few contributions have been achieved thus far and more research efforts should be dedicated to this type of watermarking so as to ensure its development.This paper makes a deep investigation into the existing removable visible wa-termarking, and based on their drawbacks, proposes two watermarking methods, namely, lossy removable visible image watermarking and reversible (also called loss-less or distortion-free) removable visible image watermarking. To ensure the security of the visible watermark, the former method pre-processes the original watermark us-ing a key-dependent strategy and then embeds the pre-processed watermark, instead of the original one, into the host image. The latter method proposes a novel encod-ing/decoding scheme for the recovery packet so that the image recovery process can be carried out without needing the availability of the watermark. In addition, the proposed watermarking approaches take the characteristics of HVS (Human Visual System) into consideration during the watermark embedding phase, thus ensuring both the visibility of the watermark and the visual quality of the host image. As demon-strated by the experimental results, the proposed methods not only reveals the visible watermark pattern in a more visible manner, but also better preserves the visual qual-ity of the host image than the existing methods. This paper will not only provide new methodology and key techniques for re-movable visible watermarking, but also offer identification technology for the appli-cations, such as forensic analysis, security check and advertising etc. The research made in this paper, therefore, plays a very important role in the social stability and development.