Difference between plt.imshow and cv2.imshow?

Question

Why is there a difference in the output image when calling the same image using plt.imshow & cv2.imshow()?

Here is my code:

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

src=cv2.imread('fruits1.jpg') # Source image

plt.subplot(211),plt.imshow(src),plt.title('image')
plt.xticks([]),plt.yticks([])
plt.show()

cv2.imshow('image',src)
cv2.waitKey(0)
cv2.destroyWindow()

Here is the image from plt.imshow:

and the second one is the original image:

Is there some modification required with the plt.imshow()?

Gwennie

OpenCV uses BGR channel ordering, but matplotlib uses RGB. So there is a channel reversal ordering between the two needed when going from one to the other. – Climax

Answer 1

Because OpenCV stores images in BGR order instead of RGB.

Try plt.imshow(cv2.cvtColor(image, cv2.COLOR_BGR2RGB))

See here for an example.

Undertaker

Answer 2

OpenCV - BGR and Matplotlib - RGB

OpenCV:

https://docs.opencv.org/2.4/doc/tutorials/introduction/display_image/display_image.html

Matplotlib:

https://matplotlib.org/api/_as_gen/matplotlib.pyplot.imshow.html

Cindiecindra

Answer 3

you can either use :

plt.imshow(cv2.cvtColor(image,cv2.COLOR_BGR2RGB))
                        OR
plt.imshow(image[:,:,::-1])  # here we are reversing the channel order

Bordie