A Robust DWT-SVD Blind Watermarking Algorithm based on Zernike Moments

Abstract

Robustness is an important index for digital watermarking. Most watermarking methods are robust to common attacks, but can not resist geometric attacks. According to the Zernike moments' rotation invariance and scale invariance, a robust DWT-SVD watermarking algorithm is presented based on Zernike moment (ZM). In this scheme, the inscribed circle of the original image matrix is selected as the ZM calculation area, and the square of the inscribed circle is chosen to embed watermark. Firstly, the watermarking embedding area is conducted with 1-level DWT and the low frequency DWT coefficient is divided into non-overlapping blocks; SVD is applied to every block. Secondly, a bit of the watermark is embedded through slight modifications of the singular value (SV) matrix in each block. Finally, some selected ZM of the watermarked image are saved to detect and correct the possible geometric attacks. The simulation has proved that the proposed not just has good resistance to rotation, scaling attacks, and as well, kinds of common signal processing, and can achieve blind extraction.