Robust template matching for affine resistant image watermarks

TLDR

Digital watermarks are used to deter illicit copying and distribution of copyrighted material. This paper proposes a method for secure and robust copyright protection of digital images. The method embeds a watermark in the Fourier transform of an image, augments it with a template to resist general linear transformations, and employs a polar‑map algorithm for accurate, efficient recovery after affine distortions. Experiments show the watermark remains robust to compression, rotation, scaling, and aspect‑ratio changes.

Abstract

Digital watermarks have been proposed as a method for discouraging illicit copying and distribution of copyrighted material. This paper describes a method for the secure and robust copyright protection of digital images. We present an approach for embedding a digital watermark into an image using the Fourier transform. To this watermark is added a template in the Fourier transform domain to render the method robust against general linear transformations. We detail a new algorithm based on polar maps for the accurate and efficient recovery of the template in an image which has undergone a general affine transformation. We also present results which demonstrate the robustness of the method against some common image processing operations such as compression, rotation, scaling, and aspect ratio changes.