how to change size of image in opencv code example

Example 1: how to change opencv capture resolution

cap.set(cv2.CAP_PROP_FRAME_WIDTH,640);
cap.set(cv2.CAP_PROP_FRAME_HEIGHT,480);

Example 2: python opencv imresize

im = cv2.resize(im, None, fx=1/3, fy=1/3, interpolation=cv2.INTER_AREA)