Enhancement of Fourier Image Watermarking Robustness

Abstract

Fourier watermarking is often chosen to watermark images that have to be printedand scanned on a physical support, during which the so-called print-scan attack occurs. Onepopular method embeds the watermark in the FFT magnitudes of the image along a circle ofoptimal radius. This paper presents an enhancement of Fourier watermarking robustness bypre-processing data to be watermarked before insertion of the watermark. This pre-processingconsists in reducing the variance of the FFT magnitudes of the image. Two schemes are proposedto reduce the variance: the rst is based on a low pass lter applied on the data, while thesecond selects the FFT magnitudes that lower the variance in a region located between twopredened circles. Results show that the robustness to print-scan attack is increased comparedto traditional Fourier watermarking. The whole scheme is ecient and has a low computationalcost that makes it compatible with industrial constraints