Video coding using global motion and brightness-variation compensation with complexity reduction

Global motion compensation and global brightness-variation compensation are proposed in order to deal with motion or brightness variation over the whole image. It is expected that the coding efficiency will be greatly improved by these techniques. The purpose of this investigation is to reduce the tremendous amount of computation which has especially hindered global brightness-variation compensation. A simple method is introduced for blockwise motion estimation processing and brightness-variation parameter estimation processing. A coding scheme is proposed, with the motion estimation procedure shared between global motion compensation and local motion compensation, so that the two functions are realized simultaneously with smaller complexity. In the case of the block size and the range of motion search in the experiment, the number of multiplications is reduced to about 1/400 as many as when the conventional compensation procedures are simply combined. As regards the coding efficiency, we demonstrate improvement integrating the effects obtained when global motion compensation and brightness-variation compensation are separately applied.