A Strategy to Select the Feature Points for Robust Zero-Watermarking Algorithm

Several watermarking techniques are proposed to protect the copyrights of digital contents. However, most of the current watermarking algorithms neglect the need of real time and resisting malicious geometric attacks. Our paper proposes a robust color image zero-watermarking scheme based on the discrete wavelet transform (DWT) and discrete cosine transform (DCT) domain with significant feature points matching for automatic rotation, scaling, translation factors in order to restore the attacked images before extracting zero-watermark. Firstly, the original image is separated into three components (Y, Cr, Cb), Then, the Y-component is performed by DWT, afterwards its LL3 is transformed with DCT. The DCT image is binarized in order to generate the mastershare. Moreover, Arnold transform is employed to scramble the watermark logo to enhance the security of the algorithm. Finally, we obtain the ownership share by performing the exclusive-or (XOR) operation between the mastershare and the scrambled watermark image, and the ownership share is stored in the copyright database for copyright authentication. In order to recover geometric attacks, we employ the robust feature points matching technique to correction algorithm without using the original image to accurately correct the attacked image. The robustness of the our proposed algorithm for imaging processes is analyzed, and the results show that the proposed algorithm is robust to common signal processing such as noise, filtering, JPEG compression, geometric attacks such as rotation, scaling, translation and so on.