CRTBased Robust Data Hiding Method by Extracting Features in DCT Domain In this paper a robust data hiding method is presented by applying Discrete Cosine Transform (DCT) to the host signal and performing feature extraction, based on Chinese Remainder Theorem (CRT). Improving the robustness reduces the imperceptibility in watermarking systems due to the tradeoff between imperceptibility, robustness and capacity in data hiding schemes. The proposed method offers high imperceptibility alongside robustness. To embed the hidden information CRT based feature extraction process is carried out in DCT domain. Extracted features are distances of CRT remainders. These distances are not varied much in noisy situations thus it is possible to extract the hidden bits with high accuracy. To analyze the robustness of the proposed method common signal processing manipulations are applied to the watermarked images. Bit Correct Rate (BCR) values are calculated for extracted watermarks to evaluate the robustness. Results are compared to other state of the art methods and confirm the superiority of the proposed method.

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.