min_image算子

*读取两张图片
read_image (Image1, 'patras')
read_image (Image2, 'brycecanyon1')
*截取两张图片相同的大小   
crop_part (Image1, ImagePart1, 0, 0, 512, 480)
crop_part (Image2, ImagePart2, 0, 0, 512, 480)
*计算两幅图像每个像素点的最小值
min_image (ImagePart1, ImagePart2, ImageMin)
*计算两幅图像每个像素点的最大值
max_image (ImagePart1, ImagePart2, ImageMax)