基于DCT变换的QWT域改进的图像盲水印算法

针对数字图像的版权保护,基于离散余弦变换和四元数小波变换,提出了一种新的改进的盲水印算法,先根据待嵌入水印的大小对载体图像进行四元数小波变换,获得与幅值和相位信息相对应的4幅低频子带,然后对每个低频子带分别进行全局离散余弦变换,最后通过修改两个随机子带中特定位置上DCT系数的大小关系嵌入水印,利用分阶线性Logistic映射产生的混沌序列预处理经Arnold置乱后的水印信息和确定水印的嵌入位置.实验结果表明,该算法对添加噪声、JPEG压缩、滤波和亮度及对比度调整等攻击都具有很强的鲁棒性.

An improved blind image watermarking algorithm based on DCT in quaternion wavelet transform domain

A novel improved blind image watermarking algorithm is proposed based on DCT in quaternion wavelet transform domain for the copyright protection of image dates.The cover image is performed with quaternion wavelet transform according to the size of watermark image to obtain four low frequency sub-bands which relevant to one amplitude and three phase information, then these sub-bands are performed with global DCT transform, finally the watermark image is embed by modifying the DCT coefficients at the particular position from two random sub-bands in order to get some numerical relationship. Piecewise linear logistic mapping is used to scramble the watermark information which has experienced Arnold transform and determine the position of watermark embedding.Experimental results show that this algorithm is robust to some common attack operations such as adding noise, JPEG compression, filter,brightness-and-contrast adjusting and so on .