opencv imshow plt imshow

opencv官方文档上写的，https://docs.opencv.org/master/dc/d2e/tutorial_py_image_display.html

Color image loaded by OpenCV is in BGR mode. But Matplotlib displays in RGB mode. So color images will not be displayed correctly in Matplotlib if image is read with OpenCV. Please see the exercises for more details.

https://stackoverflow.com/questions/15072736/extracting-a-region-from-an-image-using-slicing-in-python-opencv/15074748#15074748

import cv2
import numpy as np
import matplotlib.pyplot as plt

img = cv2.imread('messi4.jpg')
b,g,r = cv2.split(img)
img2 = cv2.merge([r,g,b])
#img2 = img[:,:,::-1]
plt.subplot(121);plt.imshow(img) # expects distorted color
plt.subplot(122);plt.imshow(img2) # expect true color
plt.show()

cv2.imshow('bgr image',img) # expects true color
cv2.imshow('rgb image',img2) # expects distorted color
cv2.waitKey(0)
cv2.destroyAllWindows()