We present a method for estimating the shutter angle, a.k.a. exposure fraction -- the ratio of the exposure time and the reciprocal of frame rate -- of videoclips containing motion. The approach exploits the relation of the exposure fraction, optical flow, and linear motion blur. Robustness is achieved by selecting image patches where both the optical flow and blur estimates are reliable, checking their consistency. The method was evaluated on the publicly available Beam-Splitter Dataset with a range of exposure fractions from 0.015 to 0.36. The best achieved mean absolute error of estimates was 0.039. We successfully test the suitability of the method for a forensic application of detection of video tampering by frame removal or insertion.
我们提出了一种方法,用于估计包含运动的视频片段的快门角度,即曝光量,即曝光时间和帧率的比值。该方法利用曝光量、光学流和线性运动模糊之间的关系。稳健性是通过选择可靠的光学流和模糊估计,并检查它们的一致性来实现的。该方法在公开可用的 beam-Splitter Dataset 上进行了评估,该数据集的曝光量范围从0.015到0.36。估计的平均值绝对误差的最佳值为0.039。我们成功地测试了该方法的 forensic 应用,即通过帧删除或插入检测视频篡改。