Abstract: A blind watermarking algorithm for color images is proposed in order to extend the range of applying.In procedures of embedding，host image in RGB space is converted to YIQ space.DWT and block-DFT are applied on it.Combining a template matrix and two pseudo random sequences，the binary watermarking image which has been scrambled by implementing Arnold transform is embedded into the host image.In procedures of extracting，embedded sequences in each image blocks are extracted.Correlations between extracted sequence and two pseudo random sequences are calculated respectively.Binary watermarking image is recovered lying on the correlation.Experimental results show the proposed algorithm has good performance in both invisibility and robustness against common image processings.

Key words: color images, blind watermarking, Discrete Wavelet Transform（DWT）, Discrete Fourier Transform（DFT）, embedded template matrix, Arnold transform, correlation

摘要： 为了扩大数字水印的适用范围，提出了一种彩色图像盲水印算法。在嵌入过程中，将宿主图像从RGB空间转换到YIQ空间，对其进行小波分解后再进行分块DFT变换，结合一个嵌入模板矩阵和两个伪随机序列，将Arnold置乱以后的二值图像水印嵌入到宿主图像中；在提取过程中，根据嵌入模板矩阵提取出嵌入到每一图像小块的序列，分别计算该序列和两个伪随机序列的相关性，根据相关性的大小关系恢复水印信息。实验结果表明，算法具有良好的不可见性和鲁棒性。

关键词: 彩色图像, 盲水印, 离散小波变换, 分块DFT, 嵌入模板矩阵, Arnold置乱, 相关性, ,