Detecting a mouth

This time, using Haar classifiers, we are going to extract a mouth position from the input video stream, and on the code below this code we are going to use those coordinates to place a mustache on the face:

import cv2 
import numpy as np 
 
mouth_cascade = cv2.CascadeClassifier('./cascade_files/haarcascade_mcs_mouth.xml') 
  
if mouth_cascade.empty(): 
  raise IOError('Unable to load the mouth cascade classifier xml file') 

cap = cv2.VideoCapture(0) 
ds_factor = 0.5 

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

    mouth_rects = mouth_cascade.detectMultiScale(gray, scaleFactor=1.7, minNeighbors=11) 
    for (x,y,w,h) in mouth_rects: 
        y = int(y - 0.15*h) 
        cv2.rectangle(frame, (x,y), (x+w,y+h), (0,255,0), 3) 
        break 

    cv2.imshow('Mouth Detector', frame) 

    c = cv2.waitKey(1) 
    if c == 27: 
    ...