A geometric robust image watermarking scheme based on DWT-SVD and Zernike moments

A new blind geometric robust watermarking scheme is presented based on singular value decomposition (SVD) and discrete wavelet transform (DWT). In the scheme, the host image is decomposed with n-level DWT and the low frequency sub-band is divided into nonoverlapping blocks. SVD is applied to every block. The watermark is embedded into the low frequency DWT coefficients by modifying the largest singular value of each block. In the detection process, the geometric distortion parameters of the attacked watermarked image are estimated first by the proposed improved geometric correction method which is based on the Zernike moments and invariant centroid. Then the watermark is extracted from the recovered image. Compared with traditional geometric estimation method, the suggested improved geometric correction method can estimate the geometric distortion parameters more accurately. The experimental results demonstrate that the proposed watermarking scheme is robust to geometric attacks, and as well, a variety of common attacks.