The Robust Image Watermarking Algorithm To Resist Geometric Attacks, Which Research

Digital watermarking for multimedia has become one of the widely used copyright protection methods. Nowadays, there is an unprecedented development in the image watermarking field. On the other hand, attacks against image watermarking systems have become more sophisticated. In general, these attacks can be categorized into common signal processing methods such as median filtering, sharpening, noise adding, and JPEG compression etc., and general geometric attacks such as rotation, scaling, translation, random bend attack, and shearing etc. While the common signal processing methods reduce watermark energy, general geometric attacks induce synchronization errors between the original and the extracted watermark during the detection process. Most of the previous image watermarking schemes are robust to common signal processing, but show severe problems to general geometric attacks. Fortunately, several approaches that counterattack the general geometric attacks have been developed in recent years.In this paper, a new rotation and scaling invariant image watermarking scheme is proposed based on rotation invariant feature and image normalization. A mathematical model is established to approximate the image based on the mixture generalized Gaussian distribution, which can facilitate the analysis of the watermarking processes. Using maximum a posteriori probability based image segmentation, the cover image is segmented into several homogeneous areas. Each region can be represented by a generalized Gaussian distribution, which is critical for the analysis of the watermarking processes mathematically. The rotation invariant features are extracted from the segmented areas and are selected as reference points. Sub-regions centered at the feature points are used for watermark embedding and extraction. Image normalization is applied to the sub-regions to achieve scaling invariance. Meanwhile, the watermark embedding and extraction schemes are analyzed mathematically based on the established mathematical model. The watermark embedding strength is adjusted adaptively using the noise visibility function and the probability of error is analyzed mathematically. The mathematical relationship between fidelity and robustness is established. The experimental results show the effectiveness and accuracy of the proposed scheme.Based on scale space theory and an image normalization technique, a new feature-based image watermarking scheme robust to general geometric attacks is proposed in this paper. First, the Harris-Laplace detector is utilized to extract steady feature points from the host image; then, the local feature regions (LFR) are ascertained adaptively according to the characteristic scale theory, and they are normalized by an image normalization technique; finally, according to the predistortion compensation theory, several copies of the digital watermark are embedded into the nonoverlapped normalized LFR by comparing the DFT mid-frequency magnitudes. Experimental results show that the proposed scheme is not only invisible and robust against common signals processing methods such as median filtering, sharpening, noise adding, and JPEG compression etc., but also robust against the general geometric attacks such as rotation, translation, scaling, row or column removal, shearing, local geometric distortion and combination attacks etc.