Watermarking through image geometry change tracking

Abstract

Most of the digital image watermarking techniques are susceptible to geometric attacks such as cropping, rotation and scaling. These attacks are the easiest yet most successful in rendering the survival of watermark difficult. Such geometric operations alter the pixel orientation in the cover thereby rendering the watermark difficult to locate and extract. However, if the alterations produced by the geometric attacks such as scaling, cropping and rotation can be modeled in terms of the change in the image geometry, it is possible to relocate the watermark even after the original cover has suffered an attack. This paper contributes to the state of the art by proposing an image watermarking technique that attempts to model the attacks like cropping, scaling and rotation in terms of the image geometry. The proposed scheme is acceptably resistant to common geometric attacks and common image processing attacks. The watermark embedding is also done efficiently to offer resistance to image processing attacks. The watermark detection procedure is blind and key based, also not requiring the original cover work for watermark extraction. Efforts have been given to ensure that the proposed scheme conforms to robustness against attacks and exhibits high visual fidelity of the watermarked cover. Keywords: Watermarking, Geometric attacks, Robust watermarking, Image geometry, Fidelity