OpenCV视频检测人脸

用opencv自带xml。打开摄像头，实时视频检测人脸

可以直接运行在linux下或者Windows下的VS中

#include <iostream>
#include <stdio.h>
#include <ctime>
#include <opencv2/opencv.hpp>
#include <opencv2/highgui/highgui.hpp>
#include <opencv2/imgproc/imgproc.hpp>
#include "opencv2/core/core.hpp"
using namespace cv;
using namespace std;

#define W 1920
#define H 1080

string face_cascade_name = "E:/opencv_VS/opencv/sources/data/haarcascades/haarcascade_frontalface_alt2.xml";
CascadeClassifier face_cascade;
int facesnum = 0;
void DectectorAndDis(Mat frame)
{
    Mat face_gray = Mat::zeros(H, W, CV_8UC3);
    vector<Rect> faces;
    cvtColor(frame, face_gray, CV_BGR2GRAY);//RGB转化为灰度
    equalizeHist(face_gray, face_gray);//直方图均衡化
    double t = (double)getTickCount();
    face_cascade.detectMultiScale(face_gray, faces, 1.75, 2, 0 | CV_HAAR_SCALE_IMAGE, Size(30, 30));
    t = ((double)getTickCount() - t)/getTickFrequency();
    
    for (int i = 0; i < faces.size(); i++){
        Point CvBox2D(int(faces[i].x + faces[i].width*0.5), int(faces[i].y + faces[i].height*0.5));
        ellipse(frame, CvBox2D, Size(int(faces[i].width*0.5), int(faces[i].height*0.5)), 0, 0, 360, Scalar(255, 0, 0), 4, 8, 0);    
     
    }
    if( facesnum != faces.size())
    {
        cout << "人脸数：" << faces.size() << endl;
        facesnum = faces.size();
        printf("本次检测使用： %0.2f ms
",t*1000);
    }
    
    imshow("读取视频", frame);
}
int main(int argc, char* argv[])
{    
    VideoCapture capture;    
    capture.open(0);
    Mat frame = Mat::zeros(H, W, CV_8UC3);
    Mat frameaftcanny = Mat::zeros(H, W, CV_8UC3);
    face_cascade.load(face_cascade_name);
    while (1)
    {
        capture >> frame;
        //cv::Canny(frame, frameaftcanny, 100, 300, 3);
        //imshow("边缘检测", frameaftcanny);
        DectectorAndDis(frame);
        cv::waitKey(20);
    }

    return 0;
}