openCV摄像头人脸检测源代码：

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    "import numpy as np\n",
    "import cv2\n",
    "face_detector = cv2.CascadeClassifier('./haarcascade_frontalface_alt.xml')\n",
    "video = cv2.VideoCapture(0)#打开电脑上的摄像头\n",
    "while True:\n",
    "    flag,frame = video.read()\n",
    "    if flag == False:\n",
    "        break\n",
    "    gray = cv2.cvtColor(frame,code = cv2.COLOR_BGR2GRAY)\n",
    "    face_zones = face_detector.detectMultiScale(gray)\n",
    "    for x,y,w,h in face_zones:\n",
    "        cv2.circle(frame,center = (x+w//2,y+h//2),radius = w//2,color = [0,0,255],thickness = 2)\n",
    "    cv2.imshow('ttnk',frame)\n",
    "    key = cv2.waitKey(41)\n",
    "    if key == ord('q'):#退出条件\n",
    "        break\n",
    "cv2.destroyAllWindows()\n",
    "video.release()"
   ]
  }
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