人脸识别分为两大步骤

1.人脸检測 这个是首要实现的。你得实现人脸显示的时候把人脸框出来，当然算法非常多，另一些人眼检測鼻子检測什么的

主要用的是这个

const char *faceCascadeFilename = "haarcascade_frontalface_alt.xml";

detect_and_draw(IplImageBuffer,storage,cascade);

这个函数就是检測人脸的并画框效果例如以下

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主要代码例如以下

void Chenaini::detect_and_draw(IplImage* img,CvMemStorage* storage, CvHaarClassifierCascade* cascade)

{

    double scale=1.2;

    static CvScalar colors[] = {

        {{0,0,255}},{{0,128,255}},{{0,255,255}},{{0,255,0}},

        {{255,128,0}},{{255,255,0}},{{255,0,0}},{{255,0,255}}

    };//Just some pretty colors to draw with

IplImage* gray = cvCreateImage(cvSize(img->width,img->height),8,1);

    IplImage* small_img=cvCreateImage(cvSize(cvRound(img->width/scale),cvRound(img->height/scale)),8,1);

    cvCvtColor(img,gray, CV_BGR2GRAY);

    cvResize(gray, small_img, CV_INTER_LINEAR);

cvEqualizeHist(small_img,small_img);     cvClearMemStorage(storage);

    double t = (double)cvGetTickCount();

        CvSize min=cvSize(0,0);

        CvSize max=cvSize(100,100);

    CvSeq *objects = cvHaarDetectObjects(                               small_img,

                                                                        cascade,storage,

                                                                        1.1,

                                                                       3, 0/*CV_HAAR_DO_CANNY_PRUNING*/,

                                                                      min,

                                                                      max

                                         );

t = (double)cvGetTickCount() - t;

    printf( "detection time = %gms\n", t/((double)cvGetTickFrequency()*1000.) );

//Loop through found objects and draw boxes around them

    for(int i=0;i<(objects? objects->total:0);++i)

    {

        CvRect* r=(CvRect*)cvGetSeqElem(objects,i);

        cvRectangle(img, cvPoint(r->x*scale,r->y*scale), cvPoint((r->x+r->width)*scale,(r->y+r->height)*scale), colors[i%8]);

    }

    for( int i = 0; i < (objects?

objects->total : 0); i++ )

    {

        CvRect* r = (CvRect*)cvGetSeqElem( objects, i );

        CvPoint center;

        int radius;

        center.x = cvRound((r->x + r->width*0.5)*scale);

        center.y = cvRound((r->y + r->height*0.5)*scale);

        radius = cvRound((r->width + r->height)*0.25*scale);

        cvCircle( img, center, radius, colors[i%8], 3, 8, 0 );

    }

QImage image(( uchar*)img->imageData, img->width, img->height, QImage::Format_RGB888);

ui->label_shipin->clear();

     ui->label_shipin->setScaledContents(true);

      ui->label_shipin->setPixmap(QPixmap::fromImage(image));

      rs = vd->unget_frame();

      cvReleaseImage(&img);

}