画出图像灰度值分布图像，然后对图像进行增强型处理，即把与特定灰度值差值大于某个特定阈值的点灰度值全部变为0，把图像凸显出来-Draw the image gray value distribution image, then the image enhancement process, that is specific to a particular gray value difference is greater than the threshold gray level value of a