Detect faces using OpenCV

facedetect.c

/*
 * Copyright 2011 Matthew Brush <mbrush(at)codebrainz(dot)ca>
 * Feel free to use this code however you want to.
 *
 * This is a VERY minimal example of detecting faces using OpenCV.  It
 * doesn't do any error handling or anything in an attempt to keep the
 * topic code more readable.
 *
 * To compile (at least on Linux):
 *   gcc -o facedetect facedetect.c `pkg-config --cflags --libs opencv`
 *
 * To run:
 *   ./facedetect CASCADE_FILE [CAMERA_INDEX]
 *
 * The CASECADE_FILEs come from the OpenCV source distribution but you
 * could also download them from the trunk's "data/haarcascades"
 * directory in the source repository:
 *   https://code.ros.org/gf/project/opencv/scmsvn
 *
 * The CAMERA_INDEX is the index of the actual capture device,
 * according to the platform. Use -1 or leave blank for the "default"
 * device.
 */
#include <cv.h>
#include <highgui.h>

#define WIN_NAME "Face Detector"

int main (int argc, char *argv[])
{
  int           i;
  int           device = -1;
  const char   *name;
  void         *handle;
  CvCapture    *capture;
  IplImage     *frame;
  IplImage     *frame_out;
  CvMemStorage *storage;
  CvSeq        *faces;
  CvRect       *rect;
  CvHaarClassifierCascade *cascade;

  if (argc > 2)
    device = atoi (argv[2]);

  storage = cvCreateMemStorage (0);
  cascade = (CvHaarClassifierCascade *) cvLoad (argv[1], 0, 0, 0);
  capture = cvCaptureFromCAM (device);

  cvSetCaptureProperty (capture, CV_CAP_PROP_FRAME_WIDTH, 320.0);
  cvSetCaptureProperty (capture, CV_CAP_PROP_FRAME_HEIGHT, 240.0);

  cvNamedWindow (WIN_NAME, 1);
  handle = cvGetWindowHandle (WIN_NAME);

  while (1)
    {
      frame = cvQueryFrame (capture);
      if (!frame)
        break;

      cvClearMemStorage (storage);

      faces = cvHaarDetectObjects (frame,
                                   cascade,
                                   storage,
                                   1.1,
                                   2,
                                   CV_HAAR_DO_CANNY_PRUNING,
                                   cvSize (40, 40),
                                   cvSize (40, 40));

      frame_out = cvCloneImage (frame);

      for (i = 0; i < (faces ? faces->total : 0); i++)
        {
          rect = (CvRect*) cvGetSeqElem (faces, i);

          cvRectangle (frame_out,
                       cvPoint (rect->x, rect->y),
                       cvPoint (rect->x + rect->width,
                                rect->y + rect->height),
                       CV_RGB (0xff,0x00,0x0),
                       1, CV_AA, 0);
        }

      cvShowImage (WIN_NAME, frame_out);

      cvReleaseImage (&frame_out);

      if (cvWaitKey (100) >= 0)
        break;

      /* Hack (at least for the GTK+ backend) to exit when the
       * window manager's close button is clicked */
      name = cvGetWindowName (handle);
      if (!name || !name[0])
        break;
    }

  cvReleaseCapture (&capture);
  cvDestroyWindow (WIN_NAME);

  return 0;
}