能区分图像或水印篡改的脆弱水印方案

针对现有脆弱型水印方案不能区分是图像内容还是水印被篡改的问题,提出一种能区分图像或水印篡改的脆弱水印方案.该方案用原始图像高7位的小波低频系数非均匀量化后生成的低频压缩图像作为水印,并用混沌系统对水印进行置乱加密,将安全性得到增强的水印直接嵌入到图像的LSB位;认证时通过差值图像定位图像内容被篡改的位置并指出图像中的水印是否被篡改.理论分析和仿真实验表明:该算法不但能精确定位图像内容被篡改的位置,而且能区分是图像内容被篡改、水印被篡改还是两者同时被篡改.

A Fragile Watermarking Scheme with Discrimination of Tampers on Image or Watermark

The existing fragile watermarking algorithms can't recognize whether the modification made to the watermarked image is on the image contents or the embedded watermark or both tampered by attackers.In this paper a fragile watermarking scheme with discrimination of tampers on image or watermark is proposed.The low-frequency compressed image,whose low-frequency wavelet coefficients of 7 Most Significant Bits(MSBs) of original image are nonuniform scalar quantization,is converted into a binary sequence as the watermark is to be embedded.The improved security watermark scrambled by chaotic systems is embedded into the LSB of the image data.During image authentication,the proposed method is able to detect the tampered location and discriminate tampers on Image or watermark from the difference image between the low-frequency compressed image and reconstructed image by watermark.Theoretic analysis and simulation results show that the proposed algorithm may not only provide excellent results of detecting the tampered location,but also indicate whether the modification made to the watermarked image is on the image contents or the embedded watermark or both.