Abstract: A new fractal watermarking scheme robust to geometric attacks is proposed based on image normalization and fractal.The geometrical invariant space is constructed by using image normalization.A significant region is obtained from the normalized image by utilizing the invariant centroid theory.The watermark is embedded into the self-similar blocks of the significant region by ajusting the DCT intermediate frequecy coefficients by fractal.Experimental results show that the scheme is invisible and robust to common signals processing and geometric attacks.

Key words: fractal watermarking, image normalization, significant region, Discrete Cosine Transformation（DCT）, geometric attacks

摘要： 以基于矩的图像归一化技术及分形相关知识为基础，提出一种可有效抵抗几何攻击的数字水印新方案。方案利用归一化技术将原始图像映射到几何不变空间内，结合不变质心理论提取出归一化图像的重要区域；利用分形，通过调整DCT中频系数，将水印自适应地嵌入到重要区域的自相似块中。仿真实验结果表明，方案不仅具有较好的透明性，而且对常规信号处理和几何攻击均具有较好的鲁棒性。

关键词: 分形水印, 图像归一化, 重要区域, 离散余弦变换, 几何攻击