Detecting Photographic Cropping Based on Vanishing Points

Cropping is a common form of manipulation, it is indiscernible and hard to detect, since the interception will not destroy most of the image's original features. In this paper, how to detect cropping according to a single image is described, and a new camera calibration algorithm into digital forensics is proposed, which conducts the calibration according to orthometric vanishing points. Our method can estimate the principal point according to a single image, science the vanishing points only depends on the direction of the object. Experiments show that our method can identify asymmetric cropping of the image effectively, and also can estimate the principal points precisely, besides it is robust to smoothing and noise.