Correcting unsynchronized zoom in 3D video

When capturing 3D video with a stereoscopic camera setup, it is important for the cameras to be precisely aligned and synchronized. This is particularly difficult in transitions such as zooming where the camera parameters must be changed in unison, or else the perceived 3D effect will be degraded. In this paper we study the problem of unsynchronized zooming in 3D video. First, we present a subjective study that shows that the perceived quality of stereo video is greatly reduced if the two views are zoomed by different amounts. Next, we present a method for correcting zoom mismatch by applying cropping and scaling to ones of the views. Our method involves finding matching points between the left and right views, and performing least-squares regressions to estimate the amount of scaling and cropping required to make the views consistent. Experiments were performed on videos with digitally introduced zoom mismatch and videos with optical unsynchronized zoom. In both cases the results show that our method is highly accurate and produces videos without size differences or vertical parallax between the two views.