一种用于彩色图像认证的脆弱性数字水印方法

针对彩色图像认证问题，提出一种基于混合视觉双稳态置乱系统的脆弱性数字水印算法。该算法将图像分块，由各块亮度值确定混沌序列长度及嵌入深度，将各点位置信息、最高有效位颜色信息，以及自定义的密钥作为混沌系统的初值，各块不同深度地将水印序列嵌入各点R,G,B分量中。检测定位时比较提取的水印和生成的水印，直接得到差异图像。理论分析及实验结果证明，使用该方法嵌入水印后图像质量高，且篡改定位能力强。

Fragile watermarking algorithm for color image authentication

A fragile watermarking algorithm based on a chaotic system is proposed for color image authentication,it divides the image into non-overlapped blocks,calculates the luminance of each block to decide the embedding depth and the length of chaotic sequence.For each pixel,an initial value is determined based on its prominent chrominance value,the position index,and the image protection key.Watermarking sequence is embedded into the embedding space of R,G,B respectively.Then it detects the temper by comparing the extracted watermarking and the produced one,so the error image is attained.Theoretical analysis and experiment result show that this algorithm to be in high quality and locate the tamper position exactly.