cv2.imshow command doesn't work properly in opencv-python

Question

I\'m using opencv 2.4.2, python 2.7 The following simple code created a window of the correct name, but its content is just blank and doesn\'t show the image:

Answer 1

Method 1:

The following code worked for me. Just adding the destroyAllWindows() didn't close the window. Adding another cv2.waitKey(1) at the end did the job.

im = cv2.imread("./input.jpg")
cv2.imshow("image", im)
cv2.waitKey(0)
cv2.destroyAllWindows()
cv2.waitKey(1)

credit : https://stackoverflow.com/a/50091712/8109630

Note for beginners:

• This will open the image in a separate window, instead of displaying inline on the notebook. That is why we have to use the destroyAllWindows() to close it later.
• So if you don't see a separate window pop up, check if it is behind your current window.
• After you view the image press a key to close the popped up window.

Method 2:

If you want to display on the Jupyter notebook.

from matplotlib import pyplot as plt
import cv2

im = cv2.imread("./input.jpg")
color = cv2.cvtColor(im, cv2.COLOR_BGR2RGB)
plt.imshow(color)
plt.title('Image')
plt.show()

Answer 2

If you choose to use "cv2.waitKey(0)", be sure that you have written "cv2.waitKey(0)" instead of "cv2.waitkey(0)", because that lowercase "k" might freeze your program too.

Answer 3

add cv2.waitKey(0) in the end.

Answer 4

I found the answer that worked for me here: http://txt.arboreus.com/2012/07/11/highgui-opencv-window-from-ipython.html

If you run an interactive ipython session, and want to use highgui windows, do cv2.startWindowThread() first.

In detail: HighGUI is a simplified interface to display images and video from OpenCV code. It should be as easy as:

import cv2
img = cv2.imread("image.jpg")
cv2.startWindowThread()
cv2.namedWindow("preview")
cv2.imshow("preview", img)

Answer 5

This is how I solve it

import cv2
from matplotlib import pyplot

img = cv2.imread('path')
pyplot.imshow(img)
pyplot.show()

Answer 6

You must use cv2.waitKey(0) after cv2.imshow("window",img). Only then will it work.

import cv2
img=cv2.imread('C:/Python27/03323_HD.jpg')
cv2.imshow('Window',img)
cv2.waitKey(0)