A new approach to global motion compensation which reduces video encoding complexity

To reduce the complexity of a video encoder, we introduce a new approach to global motion compensation related to the conventional hybrid DPCM-transform method in which the motion compensation is performed outside the feedback loop. This method is potentially useful in a variety of situations, but we focus here on an area of great interest to us- its application to the problem of video compression from remote airborne platforms. While the basic idea is conceptually similar to the pan compensation proposed by Taubman and Zakhor for their 3D subband coder, our method continually tracks and updates the image in the feedback loop in the same way as a conventional hybrid system. Using both residual energy and reconstruction error as metrics, we show that the new motion compensation scheme compares very favorably to the conventional one. We also discuss how one can achieve subpixel interpolation within the proposed framework.