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

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 benefits of Mesh-based ME (MME), the introduced algorithms are also examined in the framework of a fast MME scheme. Experimental results show the efficiency of the proposed schemes, especially when employed in the MMEa pproach, so that a reduction of more than 20% in the MF bit rate is achieved when employing typical QCIF formatted image sequences