一种用于图像内容认证的半脆弱数字水印

摘要

A semi-fragile digital watermarking for image content authentication is proposed.Firstly, the original image is decomposed through two-layer wavelet transform, then inserts the content feature which is extracted from the original image adaptively into the image coefficients based on chaotic scrambling.The watermark can be (extrcted) from the watermarked image without the original image.The integrity authentication and tamper detection are implemented by comparing the extracted watermark and the extracted content feature.Experimental result shows that this scheme is tolerant of regular manipulations.But malicious changes of the image will result in breaches of the watermark detection.In addition, this scheme can detect the exact locations-the illegal modified blocks.The algorithm applies to theimage integrity and authenticity authentication.%为了提高图像认证的可靠性,提出了一种基于图像边缘特征的半脆弱数字水印.首先对图像进行二级小波变换,在图像的细节子带中自适应地抽取反映图像内容的边缘纹理特征作为水印信息,并利用混沌系统进行加密.然后利用图像内容相邻特征确定量化步长,通过对小波系数进行量化调制来嵌入水印,水印的提取不需要原始图像.最后通过对比提取出的水印信息与重新提取出的图像边缘纹理特征,实现对待检测图像的定位认证.实验证明,该算法能够忍受常规的图像处理操作,而对恶意的篡改具有较强的敏感性和精确定位能力,适用于图像完整性和真实性认证.