基于熵准则的可变大小块匹配双向运动补偿

Variable size block matching bi-directional motion compensation based on entropy criterion

为了克服极低码率视频压缩编码中的方块效应,提出了可变大小块匹配双向运动估计和补偿方法。在编码中,每隔一帧对图像进行一次优化分割,其分割过程是对每一个宏块采用熵准则优化分割,对于非分割帧采用双向运动估计和补偿(即双向补偿帧)。所谓双向运动估计和补偿,是首先按前一帧的分割信息对其进行前向运动估计和补偿,然后由前一帧中的小块对当前帧再进行后向运动估计和补偿,对补偿过程中的重叠部分进行加权滤波。由于采用了可变大小块运动估计和补偿,同时结合后向运动估计和补偿的特点,使得双向补偿帧的预测精度有了提高。实验结果显示,对不同的视频序列,其峰值信噪比均有不同程度的提高。

A variable size block matching bi-directional motion estimation and compensation scheme was introduced. The optimal segmentation of the encoding frame was achieved by the entropy criterion. Assuming the backward frame （reference frame） was encoded by the variable size block matching backward motion estimation and compensation, then the current frame was encoded by the bi-directional motion estimation and compensation. For this frame, backward motion estimation and compensation used the segmentation information of the backward frame firstly. Then, from the backward frame to the current frame, forward motion estimation and compensation was performed on the smaller blocks. The overlapped compensation pixels were the average filter. Because it used variable sizes block matching and utilized the well performance of forward motion estimation, the prediction quality was further improved. Simulation results show that the average peak signal-noise ratio is increased with various video sequences.