上程式碼：

#coding=utf-8

import cv2
import dlib

path = "imagePath/2.jpg"
img = cv2.imread(path)
gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)

#人臉分類器
detector = dlib.get_frontal_face_detector()
# 獲取人臉檢測器
predictor = dlib.shape_predictor(
    "shape_predictor_68_face_landmarks.dat"
)
color = (0, 255, 0)  #
 
 定義繪製顏色

dets = detector(gray, 1)
g = 3
for face in dets:
    shape = predictor(img, face)  # 尋找人臉的68個標定點
    chang=[]
    kuan= []
    # 遍歷所有點，打印出其座標，並圈出來
    for pt in shape.parts():
        pt_pos = (pt.x, pt.y)
        chang.append(pt.x)
        kuan.append(pt.y)
        #cv2.circle(img, pt_pos, 1, (0, 255, 0), 1)
 

    x1 = max(chang)
    x2 = min(chang)
    y1 = max(kuan)
    y2 = min(kuan)
    cv2.rectangle(img, (x2, y2), (x1, y1), color, 1)
    cropped = img[y2 + 1:y1, x2 + 1:x1]  # 裁剪座標為[y0:y1, x0:x1]
    g = g + 1
    cv2.imwrite("imagePath/2-%d.png" % g, cropped)
'''
cv2.imshow("image", cropped)
k = cv2.waitKey(0)
if k == ord("s"):
    cv2.imwrite("imagePath/9-7.png", cropped)
 
'''
cv2.destroyAllWindows()

效果圖：