dlib表情判断给个示例

当使用dlib进行表情判断时，可以通过以下代码示例实现：

import dlib
import cv2

detector = dlib.get_frontal_face_detector()
predictor = dlib.shape_predictor('shape_predictor_68_face_landmarks.dat')
facerec = dlib.face_recognition_model_v1('dlib_face_recognition_resnet_model_v1.dat')

img = cv2.imread('path/to/image')
gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)

faces = detector(gray, 1)

for face in faces:
    landmarks = predictor(gray, face)
    face_descriptor = facerec.compute_face_descriptor(img, landmarks)
    # Do something with the face descriptor

此示例代码演示了如何使用dlib库对图像中的人脸进行识别并提取特征。