Modelling radial distortion chains for video recapture detection

This paper presents a novel cue for automatic recapture detection of videos. The problem of recapture detection is important to the field of digital forensics as recapture is often an indicator of prior tampering activity. In this paper, we tackle the problem by considering the deformation underwent by geometric primitives, such as straight lines, when processed along recapture chains.We mathematically derive a general curve model for straight lines deformed after single capture under a radial distortion model. The model is then extended to the case of recapture, demonstrating how to automatically classify videos on a per-frame basis from its compliance with a low-order radial distortion model. Finally, we test our model with a practical detector to automatically extract deformed straight lines for classification, which is applied to synthetic sequences.