ROTATION INVARIANT FEATURE EXTRACTION FOR WATERMARKING

Abstract

Keywords: Watermarking, Radon Transform, Rotation Invariant.Abstract: Many watermarks for still images are robust against common signal processing techniques, mainly JPEGcompression, noise adding and low-pass filtering, while they are sensitive to geometrical manipulations, thatyield desynchronization errors.In this paper robustness against some geometric transformations is achieved using a feature extraction methodbased on the Radon transform and whose aim is to identify an unique (and robust) feature from the imagespectrum. The embedding, which exploits the extracted feature, is based on a multiplicative rule techniqueand is applied on a suitable subset of the image Fourier transform. The properties of the extracted featureallows to resynchronize the detector and the embedded watermark even if the image undergoes geometricmanipulations (in particular rotations) as well as other processings, so that the correct watermark retrieving isguaranteed.Experimental results, lead on many standard images, confirm the effectiveness of the feature extraction methodand the robustness of the watermark against both processing and geometric transformations.