针对二值图像分块奇偶密写的统计分析

Statistical Analysis of Binary Image against Block Parity Steganography

一种实现简单的二值图像密写方法是将图像分为2×2的小块后利用边缘块的奇偶性来隐藏秘密信息.将含密图像以不同行列作边界分块时,图像块像素和的直方图存在明显差异,且非边缘块的数目变化较大.这一异常会暴露秘密信息的存在.通过将含密图像错位分块后作二次密写,并统计不同分块方式下非边缘块数目的变化量,可估计出嵌入量.该方法容易实现,实验验证了该方法的有效性.

An effective data hiding method for binary images divides the cover image into 2-by-2 blocks and embeds 1 bit in each edge block by making use of the parity of the block-sum. In this paper a steganalytic scheme is described against this technique. The proposed scheme uses difference between histograms of the block-sum when the block border is changed. By removing the top row and the left-most column to crop the suspected image, a test embedding is performed. This is used for estimating the initial embedding rate. Simulation results show that the proposed method can provide a satisfactory estimate of the embedding capacity.