Enhanced Motion Compensation Using Elastic Image Registration

In this paper we propose a method for extending the standard motion estimation algorithms used in video compression algorithms, to incorporate motion parameters that describe non-translational motion. This method uses an elastic image registration algorithm with two-dimensional discrete cosine basis functions to estimate the motion between block partitions in two video frames. A rate and a distortion are then determined for the elastic motion compensation and these are included in the mode decision calculations of the encoder algorithm. This allows the encoder to trade off bits to describe a more complex motion with bits to describe a larger residual error from a simpler translational motion model. Experimental results show an improvement in compression efficiency of 10-20% can be obtained with this enhanced motion compensation algorithm.