调色板编码中双向预测的索引值优化分配*

调色板编码中关于索引值分配对索引图编码效率的影响研究较少.因此文中提出索引值优化分配算法,利用索引图生成过程及其预测过程的双向反馈,通过正向、反向预测反馈和联合概率最大化优化索引值分配,更容易准确预测生成的索引图,提高调色板编码的效率.实验表明,相比多级预测算法,文中算法可以提高局部方向相关性预测算法的预测准确率.

Optimized Index Assignment with Bi-directional Prediction in Palette Coding

In palette coding, the research on influence of index assignment on the coding efficiency of index map is insufficient. An optimized index assignment algorithm is proposed in this paper. With the bidirectional feedback between the index map generation and prediction, the index assignment is optimized by forward prediction, backward prediction and joint probability maximization. Thus, it is easier to predict index map accurately, and the efficiency of palette coding is improved. Experimental results show that the proposed algorithm increases the prediction accuracy of the local directional prediction algorithm compared with the multi-stage prediction algorithm.