实时人脸检测

import cv2

# 加载分类器
face_cascade = cv2.CascadeClassifier('haarcascade_frontalface_default.xml')

# 开启摄像头
video_capture = cv2.VideoCapture(0)

while True:
    # 读取视频帧
    ret, frame = video_capture.read()
    
    # 检查是否成功读取了视频帧
    if not ret:
        print("无法读取视频帧")
        break

    # 将视频帧转换为灰度图像
    gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)

    # 检测人脸
    faces = face_cascade.detectMultiScale(
        gray,
        scaleFactor=1.1,
        minNeighbors=5,
        minSize=(30, 30)
    )

    # 在人脸周围绘制矩形框
    for (x, y, w, h) in faces:
        cv2.rectangle(frame, (x, y), (x + w, y + h), (0, 255, 0), 2)

    # 显示视频帧
    cv2.imshow('Video', frame)

    # 如果按下 q 键，退出循环
    if cv2.waitKey(1) & 0xFF == ord('q'):
        break

# 释放摄像头资源
video_capture.release()
cv2.destroyAllWindows()