第三章图像灰度直方图变换

代码说明：

  在数字图像处理中，灰度直方图是最简单且最有用的工具，可以说，对图像的分析与观察直到形成一个有效的处理方法，都离不开直方图。(in digital image processing, the histogram is the simplest and most useful tool, it can be said that the right image analysis and observation until the formation of an effective treatment method has been based on histogram.)