数字图像复制粘贴篡改取证  

Digital Image Forensics for Copy and Paste Tampering

作　　者：邢文博 杜志淳[1] XING Wen-bo;DU Zhi-chun(School of Criminal Justice,East China University of Political Science andLaw,Shanghai 200042,China;School of Criminal Science and Technology,Nanjing Forest PoliceCollege,Nanjing 210046,China)

机构地区：[1]华东政法大学刑事司法学院,上海200042 [2]南京森林警察学院刑事科学技术学院,南京210046

出　　处：《计算机科学》2019年第B06期380-384,396,共6页Computer Science

摘　　要：数字图像在被复制粘贴篡改时会对被复制部分进行缩放、旋转,然后粘贴在图像的不同部位,从而形成篡改图像。用sift算法检测出图像中的sift关键点,通过关键点的向量找出相互匹配的关键点对。用随机采样一致性算法在匹配点对中随机采取3个匹配点对计算其仿射变换矩阵,并对匹配图像与其仿射变换图像的局部相关图、篡改图像与点对进行循环分类,分类完成后按照每一类的仿射变换模型对篡改图像进行仿射变换以及仿射变换的逆变换,然后求得篡改其逆仿射变换图像的局部相关图。将每一类匹配关键点对按照仿射变换关系分为两组,从每组的关键点位置设置二值图像并用结构元素进行膨胀,将二值图像膨胀位置在相关图像的相关值大于阈值的膨胀部分保留,小于阈值的膨胀部分舍去,迭代膨胀到二值图像不再膨胀为止。然后获取二值图像的边界,在原图像中标出复制粘贴篡改部分。实验表明该方法可以有效定位篡改图像中的复制粘贴区域。When a digital image is tampered with copy and paste,the copied part might be zoomed,rotated and then pasted in different parts of the image.The sift key points are detected in the image by SIFT algorithm,and the matched key points are found out by matching vector of the key points.The matched key points are classified by the affine transformation matrix which is calculated byRANdom SAmple Consensus,namely randomly extracting three matched point pairs in matched point pairs.The affine transformation of the image and its inverse affine transformation are carried out.Then the local correlation map of the tampered image and its affine transformation image is obtained,and the local correlation map of the tampered image and its inverse affine transformation image too.Each class of matched key points is divided into two groups according to affine transformation relations.A binary image is set from the key point of each group and dilated with structural elements.The dilated position of the binary image is continued to have when its value in the local correlation map is greater than the threshold and is get rid of when its value in the local correlation map is less than the threshold.The binary image is dilated iteratively until it’s no longer expands and its boundary is marked on the original image.Experiments show that this method can effectively locate the copy paste tampering areas in digital images.

关 键 词：数字图像取证 sift关键点 RANSAC算法 局部相关图 复制粘贴篡改 

分 类 号：TP391[自动化与计算机技术—计算机应用技术]