一种基于改进SIFT的图像盲取证算法

针对常见的复制粘贴篡改，提出了一种基于改进SIFT（Scale Invariant Feature Transform）的图像篡改检测算法。首先，把待检测图像划分成多个矩形的ROS（Regions of Suspicion）区域，利用改进的SIFT算法提取各个ROS区域的关键点；然后，利用马氏距离原理对特征点对进行筛选与匹配，通过直线将这些匹配点连接起来，对复制粘贴区域进行准确定位。实验表明，该算法不仅降低了运算复杂度，而且对篡改区域的平移、缩放，旋转、亮度调整等，都有很好的检测和定位效果。

A Detection Algorithm of Image Forgery Based on the Improved SIFT

In view of the problem of copy-paste forgry, this paper proposes a new detection approach based on the improved scale invariant feature transform（SIFT）. Firstly,the tested image is divided into some regions of suspicion（ROS）, and the improved SIFT algorithm is applied to these regions to extract the key points and calculate the all the eigenvectors. If the tested image is tampered, those key points can be successfully matched. Secondly,in order to obtain more accurate matched feature points, Mahalanobis distance is used to improve SIFT algorithm. Finally, the copy-paste regions can be more accurately positioned by using lines between key points. The experiments demonstrate that the proposed approach can not only localize the copy forgery regions accurately, but also reduce the amount of computation and has good performance for detecting in post processing such as rotation, scaling and intensity adjustment.