Tip：載入OpenCV自帶.xml檔案。其實，這些的關鍵都是定位。注：微調引數。

# -*- coding: utf-8 -*-
"""
Created on Fri Sep 14 11:18:47 2018

@author: Administrator
"""

import cv2
#尺寸
ds_factor = 1.25
#開啟攝像頭
cap = cv2.VideoCapture(0)
if cap is None:
    raise IOError("Cannot open the webcam!")
#載入配置檔案
nose_cascade = cv2.CascadeClassifier("./data/haarcascades/haarcascade_mcs_nose.xml")
if nose_cascade.empty():
    raise IOError('Unable to load the nose cascade classifier xml file')

while True:
    ret,frame = cap.read()
    frame = cv2.resize(frame,None,fx = ds_factor,
                       fy = ds_factor,
                       interpolation = cv2.INTER_CUBIC)    
    gray = cv2.cvtColor(frame,cv2.COLOR_BGR2GRAY)
    
    #鼻子
    nose_rects = nose_cascade.detectMultiScale(gray)
    for (x,y,w,h) in nose_rects:
        cv2.rectangle(frame,(x,y),(w+x,h+y),(0,0,255),3)
        break
    cv2.imshow('Nose',frame)
    
    if cv2.waitKey(1) == 27:
        break
    
cap.release()
cv2.destroyAllWindows()