Question

I have recently been doing some circle detection in OpenCV and I have had some great success. The code below works wonderfully in C++ on a 32-bit platform. I do however have one small problem; as the program runs my RAM loads continues to load up. For example, when I start the program I am at 250mb, 30 seconds later I am at about 800mb. This continues and eventually overflows to the hard drive. I have tried to move the cvReleaseCapture inside the while loop but I just get the old “Exception at memory location….”. Any ideas how I can clean this up? Thanks a lot. Here’s the code:

#include "stdafx.h"
#include <cv.h>
#include <highgui.h>
#include <math.h>


int main( int argc, char **argv )
{
    CvCapture *capture = 0;
    IplImage  *img = 0;
    int       key = 0;
CvFont font;
cvInitFont(&font, CV_FONT_HERSHEY_PLAIN,1.0,1.0,0,1,CV_AA);

capture = cvCaptureFromCAM( 0 );

if ( !capture ) {
    fprintf( stderr, "Cannot open initialize webcam!\n" );
    return 1;
} 

cvNamedWindow( "result", CV_WINDOW_AUTOSIZE );

while( key != 'q' ) {
    img = cvQueryFrame( capture ); 
    IplImage* gray = cvCreateImage( cvGetSize(img), 8, 1 );
    CvMemStorage* storage = cvCreateMemStorage(0);
    cvCvtColor( img, gray, CV_BGR2GRAY );
    cvSmooth( gray, gray, CV_GAUSSIAN, 9, 9 );
    CvSeq* circles = cvHoughCircles( gray, storage, CV_HOUGH_GRADIENT, 2, gray-    >height/4, 200, 100, 20, 100 );
    int i;
    for( i = 0; i < circles->total; i++ )
    {
         float* p = (float*)cvGetSeqElem( circles, i );
         //cvCircle( img, cvPoint(cvRound(p[0]),cvRound(p[1])), 2, CV_RGB(0,255,0), -1, 8, 0 );
         cvCircle( img, cvPoint(cvRound(p[0]),cvRound(p[1])), cvRound(p[2]), CV_RGB(0,255,0), 2, 8, 0 );
         cvLine (img, cvPoint(cvRound(p[0]+40),cvRound(p[1])), cvPoint(cvRound(p[0]),cvRound(p[1])), CV_RGB(0,255,0), 1, CV_AA,0);
         cvLine (img, cvPoint(cvRound(p[0]),cvRound(p[1]+40)), cvPoint(cvRound(p[0]),cvRound(p[1])), CV_RGB(0,255,0), 1, CV_AA,0);
         cvLine (img, cvPoint(cvRound(p[0]-40),cvRound(p[1])), cvPoint(cvRound(p[0]),cvRound(p[1])), CV_RGB(0,255,0), 1, CV_AA,0);
         cvLine (img, cvPoint(cvRound(p[0]),cvRound(p[1]-40)), cvPoint(cvRound(p[0]),cvRound(p[1])), CV_RGB(0,255,0), 1, CV_AA,0);
         cvPutText(img, "Meow",cvPoint(cvRound(p[0]+45),cvRound(p[1]+45)), &font, CV_RGB(0,0,255)); 

    }


    if( !img ) break;       
    cvShowImage( "result", img ); 
    key = cvWaitKey( 1 );
    cvReleaseCapture( &capture );
}

cvDestroyWindow( "result" );
cvReleaseCapture( &capture );    

return 0;

}

Answer 1

Get rid of the cvReleaseCapture inside the while loop. Instead, you should have

cvReleaseMemStorage(storage);
cvReleaseImage(gray);

And you should probably move the if (!img) break; line up so it reads:

img = cvQueryFrame(capture);
if (!img) break;

Edit

Actually, instead of constantly creating and then destroying gray, you should do an initial capture (img = cvQueryFrame(capture);) outsid eof the while loop. Then create gray in the normal way. Then you don’t have to keep creating it in the while loop, which is why you’re running out of memory (you’re creating an new image every iteration without releasing it).

So

#include "stdafx.h"
#include <cv.h>
#include <highgui.h>
#include <math.h>


int main( int argc, char **argv )
{
    CvCapture *capture = 0;
    IplImage  *img = 0;
    int       key = 0;
    CvFont font;
    cvInitFont(&font, CV_FONT_HERSHEY_PLAIN,1.0,1.0,0,1,CV_AA);

    capture = cvCaptureFromCAM( 0 );

    if ( !capture ) {
        fprintf( stderr, "Cannot open initialize webcam!\n" );
        return 1;
    } 

    cvNamedWindow( "result", CV_WINDOW_AUTOSIZE );

    img = cvQueryFrame( capture );
    if (!img) 
        exit(1);
    IplImage* gray = cvCreateImage( cvGetSize(img), 8, 1 );
    CvMemStorage* storage = cvCreateMemStorage(0);

    while( key != 'q' ) {
        img = cvQueryFrame( capture ); 
        if( !img ) break;  


        cvCvtColor( img, gray, CV_BGR2GRAY );
        cvSmooth( gray, gray, CV_GAUSSIAN, 9, 9 );
        CvSeq* circles = cvHoughCircles( gray, storage, CV_HOUGH_GRADIENT, 2, gray-        >height/4, 200, 100, 20, 100 );
        int i;
        for( i = 0; i < circles->total; i++ )
        {
            float* p = (float*)cvGetSeqElem( circles, i );
            //cvCircle( img, cvPoint(cvRound(p[0]),cvRound(p[1])), 2, CV_RGB(0,255,0), -1, 8, 0 );
            cvCircle( img, cvPoint(cvRound(p[0]),cvRound(p[1])), cvRound(p[2]), CV_RGB(0,255,0), 2, 8, 0 );
            cvLine (img, cvPoint(cvRound(p[0]+40),cvRound(p[1])), cvPoint(cvRound(p[0]),cvRound(p[1])), CV_RGB(0,255,0), 1, CV_AA,0);
            cvLine (img, cvPoint(cvRound(p[0]),cvRound(p[1]+40)), cvPoint(cvRound(p[0]),cvRound(p[1])), CV_RGB(0,255,0), 1, CV_AA,0);
            cvLine (img, cvPoint(cvRound(p[0]-40),cvRound(p[1])), cvPoint(cvRound(p[0]),cvRound(p[1])), CV_RGB(0,255,0), 1, CV_AA,0);
            cvLine (img, cvPoint(cvRound(p[0]),cvRound(p[1]-40)), cvPoint(cvRound(p[0]),cvRound(p[1])), CV_RGB(0,255,0), 1, CV_AA,0);
            cvPutText(img, "Meow",cvPoint(cvRound(p[0]+45),cvRound(p[1]+45)), &font, CV_RGB(0,0,255)); 

        }

        cvShowImage( "result", img ); 
        key = cvWaitKey( 1 );

    }
    cvReleaseMemStorage(storage);
    cvReleaseImage(gray);
    cvDestroyWindow( "result" );
    cvReleaseCapture( &capture );    

    return 0;
}