理解opencv读取图片后的格式，理解图片矩阵的储存方式

python对opencv读入图片的shape理解

在高，宽，通道数上分别进行裁剪

import cv2
import numpy as np

img = cv2.imread("./image.jpg")
print(img.shape) #高，宽，通道数

cut1 = img[:30,:,:]
cv2.imwrite("./cut1.jpg", cut1)

cut2 = img[:,:30,:]
cv2.imwrite("./cut2.jpg", cut2)

cut3 = img[:,:,0]
cv2.imwrite("./cut3.jpg", cut3)