Overlapped block motion compensation: an estimation-theoretic approach

We present an estimation-theoretic analysis of motion compensation that, when used with fields of block-based motion vectors, leads to the development of overlapped block algorithms with improved compensation accuracy. Overlapped block motion compensation (OBMC) is formulated as a probabilistic linear estimator of pixel intensities given the limited block motion information available to the decoder. Although overlapped techniques have been observed to reduce blocking artifacts in video coding, this analysis establishes for the first time how (and why) OBMC can offer substantial reductions in prediction error as well, even with no change in the encoder's search and no extra side information. Performance can be further enhanced with the use of state variable conditioning in the compensation process. We describe the design of optimized windows for OBMC. We also demonstrate how, with additional encoder complexity, a motion estimation algorithm optimized for OBMC offers further significant gains in compensation accuracy. Overall mean-square prediction improvements in the range of 16 to 40% (0.8 to 2.2 dB) are demonstrated.

[1]  David Gelernter,et al.  Spending your free time , 1990 .

[2]  J. Besag On the Statistical Analysis of Dirty Pictures , 1986 .

[3]  P. Pirsch,et al.  Advances in picture coding , 1985, Proceedings of the IEEE.

[4]  John B. Shoven,et al.  I , Edinburgh Medical and Surgical Journal.

[5]  Sharad Singhal,et al.  Windowed motion compensation , 1991, Other Conferences.

[6]  Bernd Girod,et al.  The Efficiency of Motion-Compensating Prediction for Hybrid Coding of Video Sequences , 1987, IEEE J. Sel. Areas Commun..

[7]  N.G. Kingsbury,et al.  Frequency-domain motion estimation using a complex lapped transform , 1993, IEEE Trans. Image Process..

[8]  Bernd Girod,et al.  Motion-compensating prediction with fractional-pel accuracy , 1993, IEEE Trans. Commun..

[9]  Gary J. Sullivan,et al.  Multi-hypothesis motion compensation for low bit-rate video coding , 1993, 1993 IEEE International Conference on Acoustics, Speech, and Signal Processing.

[10]  Michael T. Orchard Predictive motion-field segmentation for image sequence coding , 1993, IEEE Trans. Circuits Syst. Video Technol..

[11]  M. Ohta,et al.  An overlapped block motion compensation for high quality motion picture coding , 1992, [Proceedings] 1992 IEEE International Symposium on Circuits and Systems.

[12]  Gary J. Sullivan,et al.  Motion compensation for video compression using control grid interpolation , 1991, [Proceedings] ICASSP 91: 1991 International Conference on Acoustics, Speech, and Signal Processing.