A Double Digital Watermarking Algorithm Based on the Combination of SVD-DFT

Abstract

As the most current methods based on Fourier transform domain can well resist geometric attacks, and embed large information, which cannot well resist the shearing attack, a double watermarking algorithm based on the combination of singular value decomposition and discrete Fourier transform is put forward. In this algorithm, by singular value decomposition on images, then carry out the DFT spectrum amplitude image watermark embedding on the decomposed matrix image, namely sub block division; by DFT transform on each image block, select important coefficients relative to the predefined threshold; add the watermark information into the corresponding amplitude components, and preserve the embedding position and the original component as a key for watermark extraction, and then the watermarked image will be obtained. The experimental results show that this method can achieve better visual effect and has good robustness against the shear, noise and rotation attacks.