采用整数小波变换和多目标遗传算法的可逆灰度水印  

Reversible Grayscale Watermarking Using Integer Wavelet Transform and Multi-Objective Genetic Algorithm

作　　者：邱群[1] 马小虎[1] 

机构地区：[1]苏州大学计算机科学与技术学院,苏州215006

出　　处：《计算机辅助设计与图形学学报》2015年第7期1290-1297,共8页Journal of Computer-Aided Design & Computer Graphics

基　　金：江苏省自然科学基金(BK20141195)

摘　　要：现有的可逆水印算法大部分以二值图像作为水印图像,灰度水印在嵌入之前需要转换为二值图像.为此提出一种基于人眼视觉系统、整数小波变换以及多目标遗传算法的可逆灰度水印算法.为了避免水印在嵌入过程中产生溢出的情况,需要对原始图像进行直方图修改.首先对整数小波变换之后的图像进行分块,在每一个局部块中通过像素点灰度值的大小找到满足条件的2个像素点;然后依据它们的灰度值之差与6进行模运算找到第3个像素点,通过修改找到的3个像素的灰度值嵌入水印.该算法直接以灰度图像作为水印图像,在水印嵌入之前无需对其做任何处理操作;利用人类视觉系统提高水印嵌入之后的不可见性,通过对每个子块的熵值进行归一化动态地调整水印信息的嵌入强度;然后使用遗传算法对结果进行优化,兼顾了水印嵌入之后图像的质量和不可见性.实验结果证明,文中算法易于实现、完全可逆,而且透明性好、保密性高,具有可行性.Most of the reversible watermarking algorithms currently available select binary image as water- mark, grayscale watermark should be converted to binary image before embedding. A novel reversible gray- scale watermarking algorithm based on human visual system, integer wavelet transforms and multi-objective genetic algorithm is proposed. Histogram modification is performed on the original image to prevent over- flow and underflow. Firstly, Integer wavelet transform is performed on the image, and then the coefficients are partitioned into blocks. In each local block two appropriate pixels are found through pixel gray value. Secondly, according to modulo between the gray value difference of the two pixels and six, the third appro- priate pixel is found. Watermark is embedded into image by modifying the gray values of the found pixels. The algorithm directly uses gray level image as watermark, and no preprocessing should be taken before embedding watermark. Human visual system is used to improve invisibility. The algorithm calculates wa- termarking embedding strength dynamically by normalizing entropy of each block. Genetic algorithm is used to optimize results, which meets the quality and invisibility demand after the watermark embedding. Ex- perimental results demonstrate that the proposed method is feasible and easy to implement, meanwhile it is not only completely reversible, but also effective on the transparency and confidentiality.

关 键 词：人类视觉系统 整数小波变换 遗传算法 可逆水印 

分 类 号：TP391.4[自动化与计算机技术—计算机应用技术]