1. A machine-implemented method of encoding a target image of a scene captured at a first image plane, comprising: computing a transformation mapping at least three noncollinear points substantially coplanar on a scene plane in the target image to corresponding points in a references image of the scene captured at a second image plane different from the first image plane; identifying at least one point in the target image off the scene plane and at least one corresponding point in the reference image; estimating a motion between the target image and the reference image based on the computed transformation and the identified corresponding off-scene-plane points; and encoding the target image based at least in part on the estimated motion.