A Color Image Watermarking Scheme Against Geometric Rotation Attacks Based on HVS and DCTDWT In view of poor robustness and weak resistance to geometric attack of traditional image watermarking algorithm, this paper proposes a color blind watermarking algorithm based on the combination of wavelet intermediate frequency (DWT) and discrete cosine transform (DCT). First, the original image is transformed from the RGB color spaces into the YCbCr color spaces in which the watermark is embedded into all the three color spaces. Then, the position in which watermark was embedded was chosen by Human Visual System (HVS), and the watermarking embedding is achieved by the proposed algorithm based on DCT and DWT transform. In this process, Zernike moments are used for rotation correction. The experimental results show that the algorithm is robust, and the invisible watermarkingxe2x80x99s ability of antixe2x80x93geometric xe2x80x93attacking has been improved.

Blind Multipurpose Image Watermarking Based on Secret Sharing In this paper, in order to accomplish two goals of multimedia authentication and copyright protection, we present a multipurpose watermarking method based on a commonly used cryptographic primitive called verifiable secret sharing scheme. Utilizing this primitive, our scheme achieves blindness meaning that it needs neither the original host image nor the embedded watermark. Our scheme also does not need two distinct watermarks to authenticate the images and at the same time protect their copyright. Experimental results show that the features of the shares, obtained by the used primitive from watermark, enables our method to reconstruct extracted tampered watermarks after various attacks such as JPEG compression, cropping, salt and pepper noise, median filtering, some combined attacks, etc. Comparisons are provided with other multipurpose watermarking methods which primarily aim at protecting copyright of media and authenticating it simultaneously. We also show the superiority of our proposed method to three watermarking methods attaining the goals of copyright protection and authentication.