free length meaning in Chinese

净长度
自由长度

Firstly , the system is divided into four sub systems : chinese characters recognition system , character recognition system , recognition system including characters and digits , and digital recognition system ; secondly , the statistic information about left ( right ) scan line free length of every character is used as a group feature
首先将车牌字符识别分成四个子识别系统一一汉字识另11系统、字母识别系统、字母和数字混和识别系统，以及数字识别系统:然后选择各字符的左(石)扫描线空程长度统计信息作为车牌字符的一组特征，与统计模板进行加权组合，来共同完成车牌字符的识别