DWT和DCT相结合的水印算法  

Watermarking Algorithm Combined DWT and DCT

作　　者：赖思渝[1] 王娟[2] 李明东[2] 

机构地区：[1]川北医学院医学影像系,四川南充637000 [2]西华师范大学计算机学院,四川南充637000

出　　处：《郑州大学学报（理学版）》2012年第1期66-70,共5页Journal of Zhengzhou University:Natural Science Edition

基　　金：国家自然科学基金资助项目;编号3057045

摘　　要：提出了一种基于余弦和小波变换相结合的水印嵌入方案.对水印图像进行二次置乱加密,再将一次小波分解,将得到的逼近系数和细节系数分别转换为一维序列,并量化组合生成待嵌入的二进制数据流.根据宿主图像的纹理、亮度特征将作离散余弦变换后的原图像分类,对不同的类采用不同的量化因子修改DCT系数矩阵从而实现水印的嵌入,水印检测过程不需要宿主图像的参与.实验表明该算法不仅具有良好的不可见性,而且在经过JPEG压缩、剪切、缩放、噪声添加及轻微几何变形等常见图像处理后,仍能正确提取出水印图像,水印图像压缩对码率的影响较小,适合网络传输.A watermark algorithm combined DCT and DWT was proposed.The original watermark was first performed twice scrambling and then conducted wavelet decomposition.The obtained approximate coefficients and detail coefficients were transformed to quantified one dimensional sequence and the binary data flow was prepared.And the DCT transformed host was classified according to the texture and luminance of the host.And the different quantifier was applied to different class to achieve the watermark embedding by adjusting DCT coefficients metrics without the joining of host image in watermark detection.The experimental results showed that the algorithm not only showed the perfect invisibility,but also could extract watermark correctly after suffering the JPEG compression,cropping,zooming,noise adding and slight geometric deformation.The code rates of compressed watermark image changed little.And the algorithm was suitable for network transportation.

关 键 词：DWT DCT 置乱 量化 随机序列 

分 类 号：TP391[自动化与计算机技术—计算机应用技术]