抗几何攻击图像水印方案

几何形变一直是各类数字水印算法较难抵抗的攻击手段。针对此问题，提出一种抗几何攻击数字图像水印算法。采用周期性的水印嵌入图像，强度由NVF函数确定。在检测时，用白化滤波器对图像进行预处理。由于水印数据是随机的，而图像数据高度相关，白化滤波器起到增加水印数据能量，同时降低图像数据能量的作用。由理论计算得出选择滤波器的原则。然后，通过自相关检测，得到反映几何形变的峰值点。对实验结果的分析证明，该算法对各类几何攻击都能够精确定位。

Image Watermarking Algorithm for Resisting Geometric Attack

An anti-geometric attack digital image watermarking algorithm, in which the periodic watermarking-embedded images whose intensity are determined by NVF function are adopted, is proposed to resist the geometric deformation which is difficult for many watermarking algorithm. The whitening filter is used in image pre-processing during inspection. As the watermark data is random and the image data are highly relevant, the whitening filter plays an important part in increasing the energy of watermark data and reducing the energy of image data. The principle of filter selection can be obtained by the theoretical calculation. The peak points, which reflect the geometric deformation, can be deduced by the self-correlation detection. The experimental results prove that the algorithm can pinpoint various geometric attacks.