Python OpenCV - waitKey(0) does not respond?

Question

I\'m using opencv 2.4.7 on ubuntu 12.04. I\'m programming with python and I have a problem when i run this script:

import cv2

img = cv2.imread(\'34762092361         


        

Answer 1

This will work even if you close the window using the cross button on the window.

import numpy as np
import cv2

img = cv2.imread('arvid.jpg', 0)
cv2.namedWindow('image', cv2.WINDOW_NORMAL)
cv2.imshow('image', img)

while True:
    k = cv2.waitKey(30) & 0xFF
    if k == 27:         # wait for ESC key to exit
        cv2.destroyAllWindows()
    elif k == ord('s'):  # wait for 's' key to save and exit
        cv2.imwrite('arvid2.jpg', img)
        cv2.destroyAllWindows()
    if cv2.getWindowProperty("image", 0) == -1:
        break

Answer 2

cv2.waitKey(0) means that script is in infinity loop with 0 miliseconds wait after loop .only specified key can stop it.

you did not specified end of app condition.

Try this code: Using other keys for the waitKey() function of opencv

Answer 3

This problem occurs in some earlier version of opencv. So you just need to update opencv to the latest version. Version 4.0.0.21 worked for me. Use the command below.

update opencv to version 4.0.0.21.

Answer 4

Well the use cv2.waitKeyEx(0).

It runs in the same way and waits for your response until you revoke it.

I hope it helps. Nithesh varmma

Answer 5

Adding a cv2.waitKey(1) after you destroy the window should work in this case.

cv2.imshow('imgae',img)
cv2.waitKey(0)
cv2.destroyAllWindows()
cv2.waitKey(1)

Answer 6

This code works for me from IDLE:

# -*- coding: utf-8 -*-

# Objectif : découvrir le fonctionnement d'opencv-python
# http://opencv-python-tutroals.readthedocs.org/en/latest/index.html


import numpy as np
import cv2

# Load an color image in grayscale
img = cv2.imread('Lena.tiff',0)
WINDOW_NAME = 'Image de Lena'
cv2.namedWindow(WINDOW_NAME, cv2.CV_WINDOW_AUTOSIZE)
cv2.startWindowThread()

# Display an image
cv2.imshow(WINDOW_NAME,img)
cv2.waitKey(0) 


cv2.destroyAllWindows()

Hope this helps for future readers.