基于小波变换的图象内容篡改识别与定位算法

Algorithm Used to Detect and Localize Tampers Based on DWT

提出了一种对图象内容篡改的识别与定位算法,可用于图象内容的完整性验证。首先对原始图象进行2层小波变换,将变换后的小波近似系数以相邻的4个系数(2X2)为一组,计算每组的均值,利用原始图象的HVS特性,以均值为载体嵌入水印信号,对一般的图象处理操作(有损压缩、中值滤波等),系数的均值比单个系数有较强的稳定性。提取水印时不需要原始图象,实验结果表明,该算法对一般的图象处理操作具有好的鲁棒性而对篡改攻击能准确地识别和定位。

In this paper,we propse a algorithm used to detect and localize tampers based on DWT which can be used for image authentication.We transform the image into wavelet domain and group the four adjacent wavelet coefficients.Utilizing the characteristics of the human visual system,we embed a digital signal into the average value of the four adjacent wavelet coefficients since the average value has better stability than single wavelet coefficient.This method needn't original image when extracts the watermark.Experimental results show the effectiveness of this method which is robust to common image process and fragile to malicious attack.