基于后验概率的LSB隐写分析

LSB隐写是将欲嵌入的秘密信息取代载体图像的最低比特位,是图像隐写最流行的方式之一。已经有大量算法来检测LSB隐写,但是对于图像最低位变化率的估计误差较大。探讨了一种基于后验概率的隐写分析算法：首先利用图像像素是否处于局部平滑区域进行建模,然后采用EM算法估计出图像中每个像素属于上述模型的后验概率并将后验概率作为此像素的权重,最后结合WS模型来估计图像最低位变化率。实验结果表明,该算法能有效地并且准确的估计图像最低位变化率,并且有较好的效果。

LSB steganalysis based on the posterior probability.

LSB steganography is a popular method for secret information embedding wherein the lowest bit plane of cover image is replaced by that of the embedded information. There are many efficient algorithms for LSB steganography detection, but the low bit rate change of cover image cannot be accurately estimated. In this paper, we proposes a novel method to tackle the problem by using the posterior probability. Firstly, the relationship between the image pixels and the pixels around representation is established, based on which the EM algorithm is adopted to estimate the posterior probability for each pixel, and then the posterior probabilities are taken as weights to the pixels, so that the WS model is applied to estimate the low bit rate change. Experimental results show that this method can effectively and accurately estimate the low bit rate change, and thus the performance of the LSB steganography detection algorithm is improved.