说明：  直方图及直方图均衡化，用来增加许多图像的局部对比度，尤其是当图像的有用数据的对比度相当接近的时候。通过这种方法，亮度可以更好地在直方图上分布。这样就可以用于增强局部的对比度而不影响整体的对比度，直方图均衡化通过有效地扩展常用的亮度来实现这种功能。
(Used to increase the local contrast of many images, especially when the contrast of the image of the useful data is very close to the time. In this way, the brightness could be better distributed on the histogram. This can be used to enhance the local contrast without affecting the overall contrast, histogram equalization, by effectively expanding the brightness used to achieve this functionality.)