基于DWT的一种数字水印算法  

Digital watermarking algorithm based on DWT

作　　者：张勤[1] 崔丽[1] 

机构地区：[1]北京师范大学数学科学学院 数学与复杂系统教育部重点实验室,100875

出　　处：《北京师范大学学报（自然科学版）》2015年第1期19-22,共4页Journal of Beijing Normal University(Natural Science)

基　　金：国家自然科学基金资助项目(11001017)

摘　　要：介绍了一种基于离散小波变换的数字水印算法并作了改进.原算法对水印进行Arnold置乱,由于Arnold置乱具有周期性,易被别人识破,安全性不高,新算法采用了安全性更好的混沌置乱.原算法是在高低频部分分别以2种强度嵌入水印,新算法沿用这种办法,但为了提高水印的隐蔽性和鲁棒性,新算法在第二级和第三级高频上随机选择了一些分散的嵌入点,各嵌入一半的水印.在Matlab环境中进行了对照实验,探究得出了高低频的最佳嵌入强度.攻击实验证明,在抗加噪、滤波攻击方面,新算法均有大幅度的提升;特别是在抗剪切、JPEG格式压缩攻击方面,原算法效果很差,而新算法能抵抗各种大幅度的剪切和压缩攻击.最后,二者都不能抵抗旋转攻击和抖动攻击.This paper introduced a digital watermarking algorithm based on discrete wavelet transform and made improvements.Original algorithm made watermark Arnold scrambled.Arnold scrambling is cyclical and isn't safe.New algorithm made a more safe chaostic scrambling.Original algorithm is that the high frequency part and low frequency part of watermarks are embedded into vector images in different intensities.New algorithm is the same as it.But in order to improve the watermark's invisibility and robustness,new algorithm in the second and third stages of the high-frequency part randomly selects some scattered embedded points,and are embedded with each half of watermark.Control experiments carried out in the Matlab environment got the optimal embedding strength of high frequency part and low frequency part.Attack experiments show,in the noising,filtering attacks,the new algorithm makes significant improvement.Especially in clipping,JPEG compression format attacks,the original algorithm is poor,but new algorithm can resist all kinds of substantial clipping and compression attacks.Finally,both can not resist rotation attacks and jitter attacks.

关 键 词：离散小波变换 嵌入强度 鲁棒性 混沌置乱 剪切攻击 

分 类 号：TP309.7[自动化与计算机技术—计算机系统结构]