Abstract: The Side Match(SM) inevitably causes abnormality in the pixel-value difference histogram, so there are unusual steps in the histogram of pixel-value differences. This provides a clue for steganalysis to reveal the presence of a secret message. To enhance security, a modified scheme is proposed. Classify pixel-value differences |d| into a number of continuous ranges with dynamic, which avoids occurrence of the above-mentioned steps in the pixel-value difference histogram. And adjust d to the value that is closest to the original among all the candidate values, which can effectively reduce the distortion and achieve better imperceptible. Experimental results show the effectiveness of the proposed technique.

Key words: steganagraphy, steganalysis, Side Match(SM), pixel-value difference, histogram analysis

摘要： 边缘匹配(SM)密写法会引起像素灰度差值直方图统计特性的异常，使灰度差值直方图中出现阶梯，分析者据此可以察觉秘密信息的存在。为加强安全性，提出一种改进的方案，即动态地划分差值|d|的区间，以消除阶梯效应。并在对d进行调整时，在多个候选值中选择一个与原始值最接近的，有效地减小了失真，取得了更好的视觉隐蔽性。实验证明了该方法的有效性。

关键词: 密写, 密写分析, 边缘匹配, 灰度差值, 直方图分析

CLC Number: 

• TP309.2