不同扫描方式在联合图像专家小组隐写分析方法中的应用

摘要

目前绝大部分联合图像专家小组(joint photographic experts group,JPEG)隐写方法都是通过改变DCT系数值来实现秘密信息嵌入;这种嵌入方式必然会对DCT系数的相关性造成影响,在隐写分析时挖掘DCT系数相关性很有必要.共生矩阵是挖掘DCT系数相关性的常用工具,利用该工具在提取特征前需要先对系数进行扫描.现有主流JPEG隐写分析方法主要采用行扫描或列扫描,对其他扫描方式研究较少,没有充分挖掘DCT系数相关性.针对这个问题,在研究不同扫描方式后,提出了一种新的JPEG隐写分析方法;该方法首先分析了不同扫描方式对DCT系数的块间和块内相关性的影响,然后使用多种高阶共生矩阵提取DCT系数在不同方向和距离上的相关性作为特征.针对4种隐写方法11种嵌入率的实验表明,与同类型的低维特征方法相比,该方法的检测正确率有明显提升;与同类型的高维特征方法相比,在不明显降低检测正确率的情况下,能使得特征维数得到有效控制,综合性能有一定提升.%At present,most JPEG steganographic methods embeded secret message by changing the value of DCT coefficients.The embedding method was bound to affect the dependencies existed in DCT coefficients.So it was necessary to make use of the dependencies existed in DCT coefficients in steganalysis.Co-occurrence matrices were a common tool to extract the dependencies existed in DCT coefficients.The coefficients must be scanned before extracting features using this tool.The most JPEG steganalysis methods used line scanning or column scanning and studied less on other scanning patterns.So they didn't make the most of the dependencies existed in DCT coefficients.In view of this problem,it presented an novel JPEG steganalysis based on coefficient dependencies in the paper.The inter-block and intra-block depenmencies along different scanning patterns existed in DCT coefficients was analyzed.High orders co-occurrence matrices were applied to extract different orientation and distance dependencies existed in inter-block and intra-block DCT coefficients as features.The experiments on four steganographic methods which had eleven embedding rate showed the detection accuracy of this method was improved obviously compared with similar low dimensional feature method,and this method could effectively control the feature dimension without significantly reducing the detection accuracy compared with similar high dimensional feature method.