error: (-215:Assertion failed) size.width>0 && size.height>0 in function 'cv::imshow' while video streaming from Webcam

Question

I have the next error: (-215:Assertion failed) size.width>0 && size.height>0 in function 'cv::imshow' while working with my CV project. I tried to debug this error and I have read the same issues on stackoverflow but did not find the answer for my case.

In order to debug I tried the code from OpenCV example:

import numpy as np
import cv2

cap = cv2.VideoCapture(0)
cap.isOpened()

while(True):
    # Capture frame-by-frame
    ret, frame = cap.read()

    # Our operations on the frame come here
    gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)

    # Display the resulting frame
    cv2.imshow('frame',gray)
    if cv2.waitKey(1) & 0xFF == ord('q'):
        break

# When everything done, release the capture
cap.release()
cv2.destroyAllWindows()

And there is the same error. I checked if webcam is available

cap.isOpened()

and the result is True. When I run the code the webcam LED is on.

Webcam is properly working in other applications.

score 0 · Answer 1 · answered Nov 05 '20 at 13:04

You need to check if the frame was read correctly like this:

import numpy as np
import cv2

cap = cv2.VideoCapture(0)
cap.isOpened()

while(True):
    # Capture frame-by-frame
    ret, frame = cap.read()
    if ret:
        # Our operations on the frame come here
        gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)

        # Display the resulting frame
        cv2.imshow('frame',gray)
        if cv2.waitKey(1) & 0xFF == ord('q'):
            break
       
# When everything done, release the capture
cap.release()
cv2.destroyAllWindows()

error: (-215:Assertion failed) size.width>0 && size.height>0 in function 'cv::imshow' while video streaming from Webcam

1 Answers1