Template based recovery of Fourier-based watermarks using log-polar and log-log maps

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 fast Fourier transform. To this watermark is added a template in the Fourier transform domain to render the method robust against rotations and scaling, or aspect ratio changes. We detail a new algorithm based on the logpolar or log-log maps for the accurate and ecient recovery of the template in a rotated and scaled image. 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.

A Robust Image Watermarking Method based on Contourlet Transform for Correcting Geometric Attacks

“…Even after geometric distortion, the original location is retrieved using template and extraction can be done. Implementation is complicated [6]. Multi-resolution transform proposes DHT watermarking techniques.…”

Fast Robust Template Matching for Affine Resistant Image Watermarks

“…In previous work the template consisted of a random arrangement of peaks in the FFT domain [13]. We have found experimentally that using templates of approximately 8 points works best.…”

“…Consequently methods have emerged which exploit the properties of the Discrete Fourier Transform (DFT) to achieve robustness against rotation and scaling. The DFT methods can be divided into two classes, those based on invariance [12,7] and those which embed a template into the image which is searched for during the detection of the watermark and yields information about the transformation undergone by the image [13,18]. However both these methods exploit the properties of log-polar-maps (LPM) and can only be used to detect changes of rotation and scale.…”

Data Hiding for Binary Documents Robust to Print-Scan, Photocopy and Geometric Distortions

“…In the literature, there are many papers on continuous tone (grayscale and color) images watermarking techniques resilient to rotation, scale and translation (for example [16,17,18]) and continuous tone data hiding approaches resilient to print-scan (for example [19,20]). However, none of them can be directly applied to printed binary documents.…”