为了对图像信号进行快速有效压缩，提出了一种改进的基于Hadamard变换和矢量分割的双测试算法。该算法首先在Hadamard域中对空域双测试算法的两个删除准则进行了等效变换；然后在实验的基础上，对变换域码字和输入矢量进行了恰当的矢量分割；最后在码字搜索过程中，利用其中一个最为有效的删除准则来排除大部分的不匹配码字。实验结果表明，改进算法能大大提高码字的搜索效率，搜索范围可减少到原始算法搜索范围的约14%～17%，总体编码时间也减少到原始算法编码时间的约35%～45%。

An improved double test algorithm in Hadamard transform(HT)domain is proposed in this paper.First,two kick-out conditions in original DTA method are rewritten properly in HT domain.Then,codewords and input vectors in HT domain are properly partitioned based on the result of the preliminary experiment.Finally,by using the better kick-out condition many unmatched codewords can be eliminated.The simulation shows that the search space of the improved algorithm in this paper is reduced to about 14%～17%,and the encoding time is reduced to about 35%～45% compared to the original algorithm.