活体检测

from scipy.spatial import distance
import dlib
import cv2
from imutils import face_utils

def eye_aspect_ratio(eye):
    ‘‘‘
    计算EAR值
    :param eye: 眼部特征点数组
    :return :EAR值
    ‘‘‘
    A = distance.euclidean(eye[1], eye[5])
    B = distance.euclidean(eye[2], eye[4])
    C = distance.euclidean(eye[0], eye[3])
    return (A + B) / （2.0 * C）

#通过dlib得到一个人脸检测器
detector = dlib.get_frontal_face_detector()
predictor = dlib.shape_predictor(‘libs/shape_predictor_68_face_landmarks.dat‘)    #括号中将训练文件的路径传入

#设置眼睛纵横比的阈值
EAR_THRESH = 0.3
#我们假定连续三帧以上EAR的值都小于阈值才预设是产生了眨眼操作
EAR_CONSEC_FRAMES = 3

# 人脸特征点中对应眼睛那几个特征点的序号需要定义一下
RIGHT_EYE_START = 37 - 1
RIGHT_EYE_END = 42 - 1
LEFT_EYE_START = 43 - 1
LEFT_EYE_END = 48 - 1

frame_counter = 0 #连续帧的计数
blink_counter = 0   #眨眼的计数

#开始调用摄像头
cap = cv2.VideoCaootuer(0)

while True:
    ret, frame = cap.read()
    gray = cv2.cvtColor(frame, cv2.COLOR_BGR2BRAY)    #转化成灰度图像
    rects = detector(gray, 1)   #人脸检测

    if len(rects) > 0:
        shape = predictor(gray, rects[0])    #检测特征点
        points = face_utils.shape_to_np(shape)
        leftEye = points[LEFT_EYE_START:LEFT_EYE_END + 1]   #取出左眼的特征点
        rightEye = points[RIGHT_EYE_START:RIGHT_EYE_END + 1]
        leftEAR = eye_aspect_ratio(leftEye)
        rightEAR = eye_aspect_ratdio(rightEye) #计算左右眼的EAR值
        
        #求左右眼EAR的平均值
        ear = (leftEAR + rightEAR) / 2.0

        #实际计算时，这两步非必需
        #寻找左右眼轮廓
        leftEyeHull =cv2.convexHull(leftEye)
        rightEyeHull = cv2.convexHull(rightEye)
        #绘制左右眼轮廓
        cv2.drawContours(frame, [leftEyeHull], -1, (0, 255, 0), 1)
        cv2.drawContours(frame, [rightEyeHull], -1, (0, 255, 0), 1)

       #如果EAR小于阈值，开始计算连续帧
        if ear < EAR_THRESH:
            frame_counter += 1
        else:
            if frame_counter >= EAR_CONSEC_THRESH:
                print("眨眼检测成功，请进入。")
                blink_counter += 1
                break
            frame_counter = 0

    cv2.imshow(‘window‘, frame)

    if cv2.waitKey(1) & 0xFF == ord(‘q‘):
        break

cap.realease()
cv2.destoryAllWindows()