哈德码变换域等均值等方差最近邻矢量量化码字搜索算法

本文提出一种基于哈德码变换的等均值等方差最近邻(HTEENNS)快速矢量量化码字搜索算法.在编码前,该算法预先计算每个码字的哈德码变换,然后根据各码字哈德码变换的第一维系数大小的升序排列对码字进行排序.在编码过程中,首先计算输入矢量的哈德码变换和方差,然后选取与输入矢量哈德码变换的第一维系数最近的码字作为初始匹配码字,然后利用两条有效的删除准则在该码字附近进行上下搜索与输入矢量最近的码字.测试结果表明,本文算法比等均值最近邻搜索算法(ENNS)、等均值等方差最近邻搜索(EENNS)算法和哈德码变换域部分失真搜索算法等算法有效得多.

Equal-Average Equal-Variance Nearest Neighbor Search Algorithm Based on Hadamard Transform

A fast VQ encoding algorithm,Hadamard transform (HT) based equal-average equal-variance nearest neighbor codeword search algorithm (HTEENNS),is presented.Before the search process,all codewords in the codebook are Hadamard-transformed and sorted in the ascending order of their first elements.During the search process,we firstly perform the HT on the input vector and calculate its variance,and initialize the current closest codeword of the input vector to be the codeword whose Hardamard-transformed first element is nearest to the input vector's,and secondly two efficient elimination criteria are used to find the nearest codeword to the input vector using the up-down search mechanism near the initial best-match codeword.Experimental results demonstrate that the performance of the proposed algorithm is much better than that of the ENNS,EENNS,and Hadamard transform based PDS algorithms.