It's time for a moustache

Let's overlay a moustache on top:

import cv2
import numpy as np

mouth_cascade = cv2.CascadeClassifier('./cascade_files/haarcascade_mcs_mouth.xml')

moustache_mask = cv2.imread('../images/moustache.png')
h_mask, w_mask = moustache_mask.shape[:2]

if mouth_cascade.empty():
  raise IOError('Unable to load the mouth cascade classifier xml file')

cap = cv2.VideoCapture(0)
scaling_factor = 0.5

while True:
    ret, frame = cap.read()
    frame = cv2.resize(frame, None, fx=scaling_factor, fy=scaling_factor, interpolation=cv2.INTER_AREA)
    gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)

    mouth_rects = mouth_cascade.detectMultiScale(gray, 1.3, 5)
    if len(mouth_rects) > 0:
        (x,y,w,h) = mouth_rects[0]
        h, w = int(0.6*h), int(1.2*w)
        x -= 0.05*w
        y -= 0.55*h
        frame_roi = frame[y:y+h, x:x+w]
        moustache_mask_small = cv2.resize(moustache_mask, (w, h), interpolation=cv2.INTER_AREA)

        gray_mask = cv2.cvtColor(moustache_mask_small...