Video Synchronization Based on Co-occurrence of Appearance Changes in Video Sequences

This paper presents a method for synchronizing multiple cameras from only the images captured by the cameras, assuming that they are not connected to an external clock signal source. It is assumed that The cameras are stationary and take the images of the same scene from various viewpoints, in which there are moving objects such as human in motion. The method uses the appearance changes in an image sequence as a temporal feature and matches two or more sequences by evaluating the correlation among their temporal features. We show through several experiments that the method shows good performance of synchronization in spite of its simplicity. We also present a method for synchronization in sub-frame accuracy and also for adaptively selecting regions suitable for deriving the temporal features. The latter resolves the difficulty with the case where some objects appear in some of the cameras and do not in the rest, which could deteriorate accuracy of the synchronization