import cv2
import numpy as np
 
cap = cv2.VideoCapture(0)  # 或传入0，使用摄像头
 
while(True):
 
    # 读取一帧
    _, frame = cap.read()
 
    # 把 BGR 转为 HSV
    hsv = cv2.cvtColor(frame, cv2.COLOR_BGR2HSV)
 
    # HSV中黑色范围
    lower_blue = np.array([0,0,0]) 
    upper_blue = np.array([180,255,46]) 
 
    # 获得黑色区域的mask
    mask = cv2.inRange(hsv, lower_blue, upper_blue)
 
    # 和原始图片进行and操作，获得黑色区域
    res = cv2.bitwise_and(frame,frame, mask= mask)
 
    cv2.namedWindow('frame', cv2.WINDOW_NORMAL)
    cv2.imshow('frame',frame)
    cv2.namedWindow('mask', cv2.WINDOW_NORMAL)
    cv2.imshow('mask',mask)
    cv2.namedWindow('res', cv2.WINDOW_NORMAL)
    cv2.imshow('res',res)
 
    k = cv2.waitKey(5) & 0xFF
    if k == 27:
        break
 
cv2.destroyAllWindows() 

import numpy as np
import cv2

cap = cv2.VideoCapture(0)

while(cap.isOpened()):  # check !
    # capture frame-by-frame
    ret, frame = cap.read()

    if ret: # check ! (some webcam's need a "warmup")
        # our operation on 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 is done release the capture
cap.release()
cv2.destroyAllWindows()