中文摘要：

针对现有一些彩色图像自适应水印算法在自适应过程中未充分考虑色彩信息或者在嵌入过程中未考虑彩色载体图像分量的整体性等不足,该文提出一种基于分数阶四元数傅里叶变换（Fr QFT）的彩色图像自适应数字水印算法。首先利用人类视觉系统（HVS）提取彩色载体图像块的纹理、边缘和色调掩蔽特性,并依据这些特性对适合嵌入图像块自适应分配嵌入强度,然后在Fr QFT域以自适应强度采用量化索引调制算法和冗余嵌入策略嵌入水印。实验结果表明,该算法优于现有的基于四元数傅里叶变换（QFT）的算法以及基于分数阶傅里叶变换（Fr FT）的算法,具有较好的不可见性和鲁棒性。

英文摘要：

Some existing color image adaptive watermarking algorithms do not fully utilize the color information in the adaptive process, or do not consider the holistic property of the components of a color host image. To overcome these drawbacks, this paper proposes a color image adaptive watermarking algorithm based on Fractional Quaternion Fourier Transform （FrQFT）. Firstly, the texture, edge and color tone features of the blocks of the host image are extracted using the Human Vision System （HVS）. After that, the embedding strength values of the blocks suitable to watermark embedding are set adaptively according to the extracted feature. Finally, the quantization index modulation and the multiple redundant embedding strategy are used to insert the watermark in the FrQFT domain with the adaptive strength. Experimental results show that the proposed algorithm is superior over the existing algorithm using Quaternion Fourier Transform （QFT） and the algorithm based on Fractional Fourier Transform （FrFT）.