说明：  细化算法有很多，我们在这里介绍的是一种简单而且效果很好的算法，用它就能够实现从文本抽取骨架的功能。我们的对象是白纸黑字的文本，但在程序中为了处理的方便，还是采用256级灰度图，不过只用到了调色板中0和255两项。
(There are many thinning algorithms, we have presented here is a simple but very effective algorithm, it can be achieved with the text extracted from a skeleton functions. Our object is in black and white text, but in order to deal with the convenience of the program, or use 256 grayscale, but only used a palette of 0 and 255 2.)