1. A method for generating a composite output image from an input video having a sequence of frames, the method comprising: receiving a sequence of stereo video frames depicting a foreground object; for selected frames in the sequence of stereo video frames, performing by a processing device, foreground/background segmentations to extract respective stereo foreground object images each comprising a representation of the foreground object with background pixels subtracted and storing the respective stereo foreground object images to a foreground object list, each of the stereo foreground object images having left and right images with a disparity between them; transforming the stereo foreground object images to adjust the respective disparities between the respective left and right images based on a change between a convergence depth for the respective selected frames and a convergence depth for the current frame; and overlaying the transformed stereo foreground object images onto the current frame to generate a composite output image.