A game-theoretic framework for the security system of visible watermarking

Perfect digital watermarking systems are contained two characteristics. One is the robustness that it need be resistant to geometric attacks in addition to common image processing tasks, such as JPEG compression. The other one is to preserve the image quality after embedding. However, the requirement of robustness and quality for watermark are conflicted with each other. How to determine the equilibrium of optimal security strategies between encoder and attacker and the optimal tradeoff between the intensity of embedded watermark and the perceptual translucence for visible watermark is still remained as one of the most challenging research topics in image watermarking. Therefore, in order to achieve the best tradeoff between the embedding energy of watermark, the quality of perceptual watermark translucence and the image fidelity after attacks, we propose a system architecture which is based on the game-theoretic approach that provides an optimum solution for the decision maker by studying the intensity and perceptual efficiency. The game-theoretic approach determines the transmission strategy using utility optimization according to the fluctuation of watermark states. The watermark embedding problem is formulated as a dynamic non-cooperative game with complete information while the optimal strategy is defined by the Nash equilibrium of the game. The experimental results demonstrate the feasibility of the proposed approach which allows the watermark encoder to obtain the best adaptive watermarking strategy in the different texture under attacks. Additionally, we demonstrate that the proposed system could help each user to choose the optimal transmission power to maximize its utility based on other constant parameters and resolve security issue of visual communication. (C) 2010 Elsevier Ltd. All rights reserved.