一种基于哈达玛变换与混沌理论的脆弱水印算法

传统的水印算法，通常使用小波变换对原始图像进行变换。对于复杂图像被篡改，直接的小波变换很难识别。为了准确地定位被篡改的复杂图像，提出一种基于哈达玛变换与混沌理论的脆弱水印算法。该算法首先对图像进行4x4分块，计算每一块的标准差，利用标准差小数部分和水印密钥合成为Logistic混沌映射初值生成脆弱水印。然后将脆弱水印嵌入到哈达玛变换域的直流分量中。图像认证时，不需要原始图像。实验结果表明。对于复杂图像该算法能够检测恶意篡改并进行篡改定位，是一种行之有效的图像鉴别方法。

Fragile Watermarking Algorithm Based on Hadamard Transform and Chaotic Theory

The original image is typically used to transform by wavelet transform in the traditional watermarking algorithm. If complex images has been tampered with, the directly wavelet transform is difficult to identify. In order to accurately locate the complexity of the image has been tampered, proposes a fragile watermarking algorithm based on hadamard transform and chaos theory. In this method, original image is firstly divided into 4x4 blocks, calculates the standard deviation of each block, combines the fractional part of the standard deviation and a watermarks key as the initial value of logistic maps for the generation of the fragile watermarks. Embeds the fragile watermark into the hadamard transform domain in the DC component. Image authentication have not the original image. Experimental results show that the algorithm is an effective method of identifying complex images.