Using other keys for the waitKey() function of opencv

Question

I\'m working on a program (python ,opencv) in which I use the spacebar to go to the next frame, and Esc to exit the program. These are the only two

Answer 1

I too found this perplexing. I'm running Ubuntu 18 and found the following: If the cv.imshow window has focus, you'll get one set of values in the terminal - like the ASCII values discussed above.

If the Terminal has focus, you'll see different values. IE- you'll see "a" when you press the a key (instead of ASCII value 97) and "^]" instead of "27" when you press Escape.

I didn't see the 6 digit numbers mentioned above in either case and I used similar code. It seems the value for waitKey is the polling period in mS. The dots illustrate this.

Run this snippet and press keys while focus is on the test image, then click on the terminal window and press the same keys.

    import cv2
    img = cv2.imread('test.jpg') 
    cv2.imshow('Your test image', img)

    while(1):
      k = cv2.waitKey(300)
      if k == 27:
        break
      elif k==-1:
       print "."
       continue
      else:
        print k