中文说明：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。
English Description：
In digital image processing, gray histogram is the most simple and useful tool, it can be said that the analysis and observation of the image until the formation of an effective processing method, are inseparable from the histogram.