https://blog.youkuaiyun.com/qq_41670192/article/details/80097211
import math
import cv2 as cv
import matplotlib.pyplot as plt
#读取图像,支持 bmp、jpg、png、tiff 等常用格式
img = cv.imread("E:/CV/opensource/opencv_contrib-master/modules/reg/samples/home.png")
(r, g, b) = cv.split(img)
imgg = cv.merge([b, g, r])
plt.figure("Image") # 图像窗口名称
plt.imshow(imgg)
plt.show()
cv.imshow("Image", img)