直方图均衡化，把原始图的直方图变换为均匀分布的形式，这样就增加了象素灰度值的动态范围从而可达到增强图像整体对比度的效果。-Histogram equalization, histogram of the original image is converted into the form of a uniform distribution, thus increasing the dynamic range of the pixel gray values ​ ​ of the