Otsu方法是一种全局化的动态二值化方法，又叫大津法，是一种灰度图像二值化的常用算法。该算法的基本思想是：设使用某一个阈值将灰度图像根据灰度大小，分成目标部分和背景部分两类，在这两类的类内方差最小和类间方差最大的时候，得到的阈值是最优的二值化阈值。-Otsu method is a globally-oriented dynamic binary method, also known Otsu is a gray image binarization commonly used algorithms. The basic idea of the algorithm is: set a threshold value using a grayscale image based on the size of the gray, and the background section is divided into two types of target portion, between these two classes in the minimum variance and the variance of the largest class, I get the threshold is optimal binary threshold value.