A robust global motion estimation scheme for sprite coding

A new global motion estimation technique for sprite coding is presented. The proposed system manages to accurately register frames to a sprite without referencing the sprite. This allows the motion estimation process to be performed in an environment free from the adverse influence of the sprite which is usually blurred by erroneous motion estimation. Furthermore, our system can determine the frame having the highest resolution, base frame, in the video sequence and project all other frames to the space of this base frame. This can avoid loss of information due to decimation. Moreover, the determination of the size of the sprite can be conducted before construction of the sprite which avoids clumsy manual sprite memory allocation. Experimental results show that our proposed technique estimates global motion with high accuracy and with good robustness against estimation errors, so that it is suitable for sprite coding applications in MPEG-4.