import cv2 as cv
import numpy as np


def face_detect_demo() :
    gray = cv.cvtColor(src , cv.COLOR_BGR2GRAY)
    face_detector = \
        cv.CascadeClassifier\
            ("D:/opencv/sources/data/haarcascades/haarcascade_frontalface_alt_tree.xml")
    faces = face_detector.detectMultiScale(gray , 1.02 , 5)
    vis = src.copy()
    for x , y , w , h in faces :
        cv.rectangle(src , (x , y) , (x + w , y + h) , (255 , 0 , 255) , 2)
        roi_demo = vis[x : x + w , y : y + h]#人臉提取
        cv.imshow("roi_demo" , roi_demo)
    cv.imshow("result" , src)


src = cv.imread("D:/data/lena.jpg")
cv.namedWindow("input image" , cv.WINDOW_AUTOSIZE)
cv.namedWindow("result" , cv.WINDOW_AUTOSIZE)
cv.imshow("input image" , src)
face_detect_demo()
cv.waitKey(0)
cv.destroyAllWindows()