Capture single picture with opencv

Question

I have seen several things about capturing frames from a webcam stream using python and opencv, But how do you capture only one picture at a specified resolution with python and

Answer 1

import cv2
cap = cv2.VideoCapture(0)
cap.set(3,640) #width=640
cap.set(4,480) #height=480

if cap.isOpened():
    _,frame = cap.read()
    cap.release() #releasing camera immediately after capturing picture
    if _ and frame is not None:
        cv2.imwrite('img.jpg', frame)
        cv2.imwrite(name, frame)