【作者】 王海英；

【导师】 张静；

【作者基本信息】 天津大学 ， 信号与信息处理， 2008， 硕士

【摘要】 随着计算机和网络技术的快速发展,高分辨率的数码相机以及功能强大的图像编辑软件(如:Adobe Photoshop,Microsoft Photo Editor,CorelDRAW等)的出现,图像篡改已经越来越普遍,而且,篡改后的图像难以辨别真伪。如果将篡改后的图像用于新闻媒体或法庭证物上,将会对社会造成很大的影响。因此对数字图像的真伪鉴别是非常重要的,针对图像篡改的检测,目前已经成为信息领域的研究热点。本文综述了图像篡改检测的研究现状,并基于JPEG 2000图像压缩标准的良好性能和发展前景,提出了一种基于JPEG 2000双压缩的图像篡改检测算法。文章首先分析了JPEG 2000双压缩时子带DWT系数的统计特性,及其子带DWT系数直方图傅里叶变换的幅频特性,此特性表现为:与一次压缩相比,双压缩时在幅度谱的中高频段存在较大峰值点的现象。本文利用小波变换提取出较大峰值点(奇异点),并计算出较大的峰值点所引起的极差(指极大值和极小值的差值),通过对极差取阈值来判定图像是否经过JPEG 2000二次压缩。其次,文中阐述了被篡改的JPEG 2000图像中篡改区域和未篡改区域可分的依据,并根据此依据提出了定位篡改区域的方法。实验表明,本文提出的算法不仅能有效检测出JPEG 2000双压缩,而且还可对图像的篡改区域进行准确定位。更多还原

【Abstract】 With the rapid and extensive development of computer and network technique, the emergence of high resolution digital caneras,and sophisticated photo-editing software (such as Adobe Photoshop,Microsoft Photo Editor,CorelDRAW), doctored images can be found anywhere,moreover,they are hard to distinguish from authentic photographs.These forgeries, if used in the mass media or courts of law, can have an important impact on our society. It is very important to detect the doctored images. Therefore the detection of doctored images has became a research focus in the information field.This dissertation summarizes the research status of tamper detection, and based on the good performance and development prospects of JPEG 2000 image compression standard, this dissertation proposes a method of detecting doctored double JPEG 2000 images. The dissertation analyses the statistics properties of double JPEG 2000 compression, and the artifacts in the Fourier transforms of subband DWT coefficients histogram, that is,compared with the first compression, stronger peaks are visible in the mid and high frequencies. Based on the characteristics of Wavalet transform which can be used to locate the singularity (peaks), then,according to the range(the difference of maximum and minimum),which is induced by the peaks,we propose a method of detecting double JPEG 2000 compression. The dissertation points out that it is divisible of doctored blocks and undoctored blocks, and so a simple and effective method is used to locate the doctored part.The experiments show that this algorithm not only can detect double JPEG 2000 compression, but also can accurately locate the doctored part.更多还原