Dept. of Electr. and Comput. Eng., Illinois Univ., Urbana, IL.
IEEE Trans Image Process. 1994;3(5):693-9. doi: 10.1109/83.334974.
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.
我们提出了一种运动补偿的估计理论分析，当与基于块的运动矢量场一起使用时，会导致具有改进补偿精度的重叠块算法的发展。重叠块运动补偿 (OBMC) 被表述为一种概率线性估计器，用于根据解码器可用的有限块运动信息来估计像素强度。虽然已经观察到重叠技术可以减少视频编码中的块效应伪像，但该分析首次确定了 OBMC 如何（以及为什么）即使在不改变编码器搜索且没有额外的侧信息的情况下，也可以提供显著的预测误差减少。通过在补偿过程中使用状态变量条件化，可以进一步提高性能。我们描述了用于 OBMC 的优化窗口的设计。我们还展示了，通过增加编码器的复杂性，针对 OBMC 进行优化的运动估计算法如何提供更高的补偿精度。总体而言，平均预测改进在 16%至 40%（0.8 至 2.2dB）之间。
