human face detection

face_detection.cc

#include <stdio.h>
#include <opencv2/opencv.hpp> // for highgui, core etc.

using namespace cv;

// cascade : classifier using to detect haar objects.
// storage : memory to store detected objects.
void DetectAndDraw(CvHaarClassifierCascade* cascade, 
                   CvMemStorage* storage, 
                   IplImage* img, 
                   double scale = 1.3) {

  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 angles.

  printf("Detecting objects ... \n");
  // Detect Objects
  cvClearMemStorage(storage);
  CvSeq* objects = cvHaarDetectObjects(
        img,
        cascade,
        storage,
        scale,
        2,
        0,
        cvSize(30, 30)
      );
  
  printf("%d objects found !\n", objects ? objects->total:0);
  // Loop found objects and draw angles around them.
  for(int i=0; i<(objects ? objects->total:0); i++) {
    printf("drawing...\n");
    CvRect* r = (CvRect*)cvGetSeqElem(objects, i);
    cvRectangle(
        img, 
        cvPoint(r->x, r->y),
        cvPoint(r->x + r->width, r->y + r->height),
        colors[i%8]
        );
  }

  cvNamedWindow("Example");
  cvShowImage("Example", img);
  cvWaitKey(0);
  cvDestroyWindow("Example");
}

int main( int argc, char** argv )
{
  CvMemStorage* storage = cvCreateMemStorage(0);
  const char* cascade_name = "haarcascade_frontalface_alt2.xml";
  CvHaarClassifierCascade* cascade = (CvHaarClassifierCascade*)cvLoad(cascade_name, 0, 0, 0);
  if (!cascade) {
    printf("Load cascade failed !\n");
    exit(-1);
  }

  IplImage* img = cvLoadImage(argv[1]);
  DetectAndDraw(cascade, storage, img);

  // Release allocated memory.
  cvReleaseMemStorage(&storage);
  cvReleaseImage(&img);
  cvReleaseHaarClassifierCascade(&cascade);

  return 0;
}