// compile with:
//   g++ `pkg-config opencv --libs` `pkg-config opencv --cflags` -o canny canny.c
// start with
//   canny some_image.png

#include <cv.h>
#include <highgui.h>

int main(int argc, char* argv[])
{
  IplImage* pImg = cvLoadImage(argv[1]) ;
  if (!pImg)
    exit(EXIT_FAILURE);
  
  IplImage* pGVImg = cvCreateImage(cvGetSize(pImg), IPL_DEPTH_8U, 1);
  cvSplit(pImg, pGVImg, NULL, NULL, NULL );
  
  IplImage* pCannyImg = cvCreateImage(cvGetSize(pImg), pImg->depth, 1);
  cvCanny(pGVImg, pCannyImg, 40, 130);
  
  cvNamedWindow("Canny", CV_WINDOW_AUTOSIZE) ;
  cvShowImage("Canny", pCannyImg);

  cvWaitKey(0);

  cvDestroyWindow("Canny");
  cvReleaseImage(&pCannyImg) ;
  cvReleaseImage(&pGVImg) ;
  cvReleaseImage(&pImg) ;

  return EXIT_SUCCESS;
}