伴随着多媒体数字版权技术的不断发展以及数字权益保护技术对数字水印鲁棒性要求的不断提高,越来越多的研究者正日益关注水印算法对各种攻击的抵抗能力,特别是抗几何攻击能力.对现有的五种抗几何攻击的典型水印算法:(i)基于傅立叶一梅林变换的抗几何形变水印算法;(ii)基于标准化嵌入和提取的抗几何形变水印算法;(iii)基于Zernike矩的抗几何形变水印算法;(iv)基于水印的自相似分形变换的抗几何形变水印算法;(v)基于图像特征点定位的抗几何形变水印算法做以简单介绍和比较,最后给出几何形变数字水印算法的性能评价函数,包括峰值信噪比和归一化相关系数.
With the development of digit multimedia copyright technology and the continuously improving request for the robust watermarking in digital right protection, more and more researchers are increasingly concerned about the watermarking algorithm's resistance to various attacks especially for geometric attack. This paper first introduces and compares five kinds of conventional anti - geometric watermarking algorithms including: (i)Fourier-Mellin transform; (ii)normalizing embedding and fetching; fiii)Zernike moment; (iv) Self-similar fractal transform; (V)Feature point locating. In the end, this paper gives the performance evaluation criteria of anti-geometric watermarks: peak signal noise ratio and normalized cross-correlation.