OpenCV follows BGR order, while matplotlib follows RGB order.

when you display an image loaded in OpenCV using pylab functions, you may need to convert it into RGB mode.  Below method demonstrate it: (三种方法，任选一种即可)

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

img = cv2.imread('peppers.bmp',-1)
# method 1 
b,g,r = cv2.split(img)
img2 = cv2.merge([r,g,b])

# method 2
b,g,r = im[:,:,0],im[:,:,1],im[:,:,2]
img2 = cv2.merge([r,g,b])

# method 3
img2 = im[:,:,::-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()

Run this code and see the difference in result yourself. Below is what I got :

Using Matplotlib :

Using OpenCV :