中文摘要：

提出了一种基于离散小波变换（DWT）及四元数傅里叶变换（QDFT）的鲁棒性全息水印算法。首先对RGB彩色图像的三个色彩分量分别做DWT,取变换后的3个低频部分组成纯四元数矩阵;随后对其进行QDFT,将全息水印通过替代QDFT的实部的中频系数进行嵌入,再经过逆QDFT及小波重构得到含有水印的彩色图像。攻击测试结果表明,本文算法对于常规的信号处理有很好的鲁棒性;打印扫描实验证明,本文算法具有抵抗硬拷贝攻击的能力。四元数傅立叶变换的引入,实现了小波低频系数的嵌入保证了算法的鲁棒性,同时又结合了四元数在处理彩色图像中的优势,双变换域的采用与全息方法的结合实现了算法应用于硬拷贝彩色图像中鲁棒性及不可见性之间的平衡。本文全息水印方案可以应用于印品水印防伪领域。

英文摘要：

In order to improve the robustness of the holographic watermarking algorithm in discrete wavelet domain,we propose a robust hologram watermarking scheme based on discrete wavelet transform（DWT）and quaternion discrete Fourier transform（QDFT）,which can be used in hardcopy color image.Firstly,for getting a robustness embed area,we conducted DWT on the three color components of the host color image and got their low frequency coefficients to construct a pure quaternion matrix.Then the middle frequency region of the real part of QDFT coefficient was replaced by holographic watermark information.By inverse QDFT and wavelet reconstruction,we finally got the watermarked color image.Experimental results demonstrate that the proposed algorithm achieves good performance in robustness against both common signal operations and print-and-scan attack.Computer-generated holography technology and low frequency wavelet coefficient domain embedding manner provide a robustness guarantee.The quaternion used in processing color image makes the algorithm have good performance in invisibility even the low frequency information of the host image is modified,and provides a more covert embedding area combined with transform domain.