Displaying image without waitKey

Question

This Python code displayed an image in full screen:

blank_image = cv2.imread('blank.jpg')
cv2.namedWindow("bw", cv2.WND_PROP_FULLSCREEN)          
cv2.setWindowProperty("bw", cv2.WND_PROP_FULLSCREEN, cv2.cv.CV_WINDOW_FULLSCREEN)
cv2.imshow("bw", blank_image)
cv2.waitKey(0)

The problem is the code is going to run on a Linux machine without keyboard. Calling waitKey means the UI processing will not be done until a key event occurs, and thus the contradiction.

Is there any way beside the waitKey, then?

Answer 1

Just to clarify: from the docs you can see that

Python: cv2.waitKey([delay]) → retval

The function waitKey waits for a key event infinitely (when delay <= 0 ) or for delay milliseconds, when it is positive.

If you use the delay = 0, then your program waits for a key event infinitely, blocking the execution. As @Miki said, you can use delay = 1, so that waitKey won't block.

Answer 2

You can use matplotlib library for displaying images in python.

In [9]: blank_image = cv2.imread('blank.jpg')
In [10]: import matplotlib.pyplot as plt
In [11]: plt.ion()
In [12]: plt.imshow(blank_image)
Out[12]: <matplotlib.image.AxesImage at 0x7fb3cf31bf10>