1. 安装Python， 略。

2. 安装 OpenCV:        

pip install opencv-python

3. 预览摄像头画面脚本：

import cv2cap = cv2.VideoCapture(0, cv2.CAP_DSHOW)if not (cap.isOpened()):print("Could not open video device")cap.set(cv2.CAP_PROP_FRAME_WIDTH, 640)
cap.set(cv2.CAP_PROP_FRAME_HEIGHT,480)
cap.set(cv2.CAP_PROP_FOURCC, cv2.VideoWriter.fourcc('Y', 'U', 'Y', 'V'))while(True):    # Capture frame-by-frame    ret, frame = cap.read()    cv2.imshow('frame', frame)#Waits for a user input to quit the application    if cv2.waitKey(1) & 0xFF == ord('q'):    breakcap.release()
cv2.destroyAllWindows()