New Half-Pixel Accuracy Motion Estimation Algorithms for Low Bitrate Video Communications


1 Department of Computer Science and Engineering,Sharif University of Technology

2 Department of Electrical Engineering,Azad University


Fractional-pixel accuracy Motion Estimation (ME) has been shown to result in higher quality
reconstructed image sequences in hybrid video coding systems. However, the higher quality is
achieved by notably increased Motion Field (MF) bitrate and more complex computations. In this
paper, new half-pixel block matching ME algorithms are proposed to improve the rate-distortion
characteristics of low bitrate video communications. The proposed methods tend to decrease the
required video bandwidth, while improving the motion compensation quality. The key idea is to
put a deeper focus on the search origin of the ME process, based on center-bias characteristics
of low bitrate video MFs. To employ the bene ts of Mesh-based ME (MME), the introduced
algorithms are also examined in the framework of a fast MME scheme. Experimental results
show the eciency of the proposed schemes, especially when employed in the MME approach,
so that a reduction of more than 20% in the MF bitrate is achieved when employing typical
QCIF formatted image sequences.