Builtin camera is unable to capture frame using cv2.VideoCapture()

Question

I'm trying to learn OpenCV. How do I capture an image frame from a builtin webcam using cv2.VideoCapture() ?

import cv2, time
video = cv2.VideoCapture(0, cv2.CAP_DSHOW)

video.release()
check,frame = video.read()
print(check)
print(frame)
time.sleep(3)

cv2.destroyAllWindows()

This produces the following output:

False
None

Why does it return False ?

Answer 1

Read the docs for VideoCapture::release . According to them it

Closes video file or capturing device.

That's not what you want. Remove the video.release() . Then VideoCapture::read() should succeed.

Starting out with OpenCV it's often easiest to start from some tutorial code and then modify as needed. For example, this tutorial is the first thing that comes up for a search for "OpenCV VideoCapture tutorial":

import cv2

cap = cv2.VideoCapture(0)

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()