old_contents: import cv2
  
  
  def webcam_gui(filter_func, video_src=0):
  
      cap = cv2.VideoCapture(video_src)
      key_code = -1
      
      while(key_code == -1):
          t = cv2.getTickCount()
          # read a frame
          ret, frame = cap.read()
          fps = cv2.getTickFrequency() / (cv2.getTickCount() - t) 
          print("Frame rate: " + str(fps))
          
          # run filter with the arguments
          frame_out = filter_func(frame)
          
          # show the image
          cv2.imshow('Press any key to exit', frame_out)
          
          # wait for the key
          key_code = cv2.waitKey(10)
  
      cap.release()
      cv2.destroyAllWindows()
  
  
          
  
  def edge_filter(frame_in):
      # convert into gray scale
      frame_gray = cv2.cvtColor(frame_in, cv2.COLOR_BGR2GRAY)
      # blur the image to reduce noise
      frame_blur = cv2.blur(frame_gray, (3,3))
      # Canny edge detection
      frame_out = cv2.Canny(frame_blur, 30, 120)
      
      return frame_out
  
      
      
  def gray_filter(frame_in):
      # convert into gray scale
      frame_out = cv2.cvtColor(frame_in, cv2.COLOR_BGR2GRAY)
      
      return frame_out
      
      
      
  if __name__ == "__main__":
      webcam_gui(gray_filter, video_src=1)
  
new_contents: import cv2
  
  
  def webcam_gui(filter_func, video_src=0):
  
      cap = cv2.VideoCapture(video_src)
      key_code = -1
      
      while(key_code == -1):
          t = cv2.getTickCount()
          # read a frame
          ret, frame = cap.read()
          fps = cv2.getTickFrequency() / (cv2.getTickCount() - t) 
          print("Frame rate: " + str(fps))
          
          # run filter with the arguments
          frame_out = filter_func(frame)
          
          # show the image
          cv2.imshow('Press any key to exit', frame_out)
          
          # wait for the key
          key_code = cv2.waitKey(10)
  
      cap.release()
      cv2.destroyAllWindows()
  
  
          
  
  def edge_filter(frame_in):
      # convert into gray scale
      frame_gray = cv2.cvtColor(frame_in, cv2.COLOR_BGR2GRAY)
      # blur the image to reduce noise
      frame_blur = cv2.blur(frame_gray, (3,3))
      # Canny edge detection
      frame_out = cv2.Canny(frame_blur, 30, 120)
      
      return frame_out
  
      
      
  def gray_filter(frame_in):
      # convert into gray scale
      frame_out = cv2.cvtColor(frame_in, cv2.COLOR_BGR2GRAY)
      
      return frame_out
      
      
      
  if __name__ == "__main__":
      webcam_gui(gray_filter, video_src=0)
  
subject: use default camera