old_contents: # coding:utf-8
  import cv2
  
  cap = cv2.VideoCapture(0)
  cascade_path = "../opencv/data/haarcascades/haarcascade_frontalface_default.xml"
  cascade = cv2.CascadeClassifier(cascade_path)
  
  over_imgae_path = "./over.png"
  over_image = cv2.imread(over_imgae_path, cv2.IMREAD_UNCHANGED) 
  
  mask = over_image[:,:,3]  # extract alpha channel
  mask = cv2.cvtColor(mask, cv2.COLOR_GRAY2BGR)
  over_image = cv2.imread(over_imgae_path) # no alpha
  
  _response, frame = cap.read()
  minsize = (int(frame.shape[0] * 0.1), int(frame.shape[1] * 0.1))
  
  while True:
      _response, frame = cap.read()
      facerect = cascade.detectMultiScale(frame, scaleFactor=1.11, minNeighbors=3, minSize=minsize)
  
      for rect in facerect:
          x, y, w, h = rect
          oi = cv2.resize(over_image, (w, h))
          rmask = cv2.resize(mask, (w, h))
          rmask = rmask <= 1
  
          frame[y:y+h, x:x+w] *= rmask
          frame[y:y+h, x:x+w] += oi
  
      cv2.waitKey(1)
      cv2.imshow("face camera", frame)
  
new_contents: # coding:utf-8
  import cv2
  
  cap = cv2.VideoCapture(0)
  cascade_path = "../opencv/data/haarcascades/haarcascade_frontalface_default.xml"
  cascade = cv2.CascadeClassifier(cascade_path)
  
  over_imgae_path = "./over.png"
  over_image = cv2.imread(over_imgae_path, cv2.IMREAD_UNCHANGED) 
  
  mask = over_image[:,:,3]  # extract alpha channel
  mask = cv2.cvtColor(mask, cv2.COLOR_GRAY2BGR)
  over_image = cv2.imread(over_imgae_path) # no alpha
  
  _response, frame = cap.read()
  minsize = (int(frame.shape[0] * 0.1), int(frame.shape[1] * 0.1))
  
  while True:
      _response, frame = cap.read()
      facerect = cascade.detectMultiScale(frame, scaleFactor=1.11, minNeighbors=3, minSize=minsize)
  
      for rect in facerect:
          x, y, w, h = rect
          oi = cv2.resize(over_image, (w, h))
          rmask = cv2.resize(mask, (w, h))
          rmask = rmask <= 1
  
          frame[y:y+h, x:x+w] *= rmask
          frame[y:y+h, x:x+w] += oi
  
      key = cv2.waitKey(1)
      if key == ord("\r"):
          cv2.imwrite("./camera.png", frame)
          print("save picture.")
  
      cv2.imshow("face camera", frame)
  
subject: Add picture save function