说明：  本文首先介绍完整的文档处理系统以及其预处理模块，然后将重点放在二值化问题上，给出图像阈值化方法的综述，并对全局阈值化、局部动态阈值化等方法的优点和缺点给出评价。
(This paper introduces a complete document processing system and its preconditioning module, then will focus on two issues of value, the threshold value is given image synthesis method, and the overall threshold, Local dynamic threshold, such as the advantages and disadvantages are given evaluation.)