如何在OpenCV - python中检测到人脸时绘制圆圈

import cv2
import numpy as np

face_cascade = cv2.CascadeClassifier('path_to_face_cascade.xml')

image = cv2.imread('path_to_image.jpg')
gray = cv2.cvtColor(image, cv2.COLOR_BGR2GRAY)

faces = face_cascade.detectMultiScale(gray, scaleFactor=1.1, minNeighbors=5, minSize=(30, 30))

for (x, y, w, h) in faces:
    center = (x + w // 2, y + h // 2)
    radius = min(w, h) // 2
    cv2.circle(image, center, radius, (0, 255, 0), 2)

cv2.imshow('Detected Faces', image)
cv2.waitKey(0)
cv2.destroyAllWindows()