中文说明： 提供了一些常用的图像预处理的代码，可以满足所有基本预处理的需要，包括读入图像，图像灰度转换，阀值，图像反色， 灰度线性变换，直方图均衡化，线性平滑滤波器，中值滤波器等。
English Description：
Code that provides some common image pre-processing, can meet all essential pretreatment needs, including Read images, grayscale conversion, threshold, invert the colors of the image, Gray level transformation, histogram equalization, linear smoothing filter, median filter, and so on.