关键词: 矢量量化, 码字搜索, 快速相关, 相关预测, 图像编码

Abstract: On the basis of high coding quality，reducing encoding time and cutting down bit rates are the important problems of current research in vector quantization.Fast codeword search algorithm is an important technology to reduce encoding time.This paper presents a Modified Hadamard-Transform based Equal-average Equal-variance Nearest Neighbor Search algorithm（MHTEENNS）.The experiment shows that this algorithm can exclude more codeword and is more efficient.In order to reduce bit rates，and reduce more encoding time，fast correlation vector quantization algorithm is presented，but coding quality is declined.This paper presents a Modified Diagonal based Fast Correlation Vector Quantization algorithm（MDFCVQ）.The experiment shows that the algorithm can improve the quality by 0.8~0.9 dB and reduce bit rates.Finally，this paper combines fast codeword search algorithm and correlation vector quantization.Compared with previous algorithm，a new algorithm is presented，which has higher quality and lower bit rates.

Key words: Vector Quantization（VQ）, codeword search, fast correlation, correlation predictive, image coding