基于混沌映射的半脆弱图像水印算法

水印的安全性、抗常规图像处理的鲁棒性和篡改检测能力的矛盾、计算复杂度等是现有基于半脆弱水印技术的图像认证算法需克服的主要问题。提出了一种基于混沌映射的自适应半脆弱水印算法，选取图像小波变换的低频信息作为图像特征并利用混沌映射对初值的敏感性产生两种水印，采用块均值量化调制小波系数的方法完成水印信息的嵌入。实验结果表明，该算法具有一定的鲁棒性，可将JPEG压缩等常规信号处理与恶意篡改相区分，并能准确定位篡改区域。

Semi-fragile Image Watermarking Algorithm Based on Chaotic Map

How to ensure watermark security,how to cancel out the contradiction between robustness to common image processing and fragility to malicious tamper, and how to reduce the computational complexity are the main issues to be solved in the existing image authentication algorithms based on semi-fragile watermarking technique.Presents a new chaos-based adaptive semi-fragile watermarking algorithm which extracts features from the low frequency domain and uses the high sensitivity on initial value of chaotic mapping to generate two watermarks,then embeds them back into the image by mean-quantization and modulating the wavelet coefficients.Experimental results show that the algorithm can identify intentional content modification and incidental tampering and also indicate the location where a modification takes place.