обнаружение формы opencv

Привет я использую OpenCV для простого обнаружения формы обнаружения (треугольники, многоугольники, круги)
и вот мой код:

   int main()
{

IplImage* img =  cvLoadImage("C:/Users/tarek/Desktop/test5.png");

//show the original image
cvNamedWindow("Raw");
cvShowImage("Raw",img);

//converting the original image into grayscale
IplImage* imgGrayScale = cvCreateImage(cvGetSize(img), 8, 1);
IplImage* imgCanny = cvCreateImage(cvGetSize(img), 8, 1);
cvCvtColor(img,imgGrayScale,CV_BGR2GRAY);

//thresholding the grayscale image to get better results
cvThreshold(imgGrayScale,imgGrayScale,128,255,CV_THRESH_BINARY);

CvSeq* contours;  //hold the pointer to a contour in the memory block
CvSeq* result;   //hold sequence of points of a contour
CvMemStorage *storage = cvCreateMemStorage(0); //storage area for all contours

//finding all contours in the image
cvFindContours(imgGrayScale, storage, &contours, sizeof(CvContour), CV_RETR_LIST, CV_CHAIN_APPROX_SIMPLE, cvPoint(0,0));

//iterating through each contour
while(contours)
{
//obtain a sequence of points of contour, pointed by the variable 'contour'
result = cvApproxPoly(contours, sizeof(CvContour), storage, CV_POLY_APPROX_DP, cvContourPerimeter(contours)*0.02, 0);

//if there are 3  vertices  in the contour(It should be a triangle)
if(result->total==3 )
{
//iterating through each point
CvPoint *pt[3];
for(int i=0;i<3;i++){
pt[i] = (CvPoint*)cvGetSeqElem(result, i);
}

//drawing lines around the triangle
cvLine(img, *pt[0], *pt[1], cvScalar(255,0,0),4);
cvLine(img, *pt[1], *pt[2], cvScalar(255,0,0),4);
cvLine(img, *pt[2], *pt[0], cvScalar(255,0,0),4);

}

//if there are 4 vertices in the contour(It should be a quadrilateral)
else if(result->total==4 )
{
//iterating through each point
CvPoint *pt[4];
for(int i=0;i<4;i++){
pt[i] = (CvPoint*)cvGetSeqElem(result, i);
}

//drawing lines around the quadrilateral
cvLine(img, *pt[0], *pt[1], cvScalar(0,255,0),4);
cvLine(img, *pt[1], *pt[2], cvScalar(0,255,0),4);
cvLine(img, *pt[2], *pt[3], cvScalar(0,255,0),4);
cvLine(img, *pt[3], *pt[0], cvScalar(0,255,0),4);
}

//if there are 7  vertices  in the contour(It should be a heptagon)
else if(result->total ==7  )
{
//iterating through each point
CvPoint *pt[7];
for(int i=0;i<7;i++){
pt[i] = (CvPoint*)cvGetSeqElem(result, i);
}

//drawing lines around the heptagon
cvLine(img, *pt[0], *pt[1], cvScalar(0,0,255),4);
cvLine(img, *pt[1], *pt[2], cvScalar(0,0,255),4);
cvLine(img, *pt[2], *pt[3], cvScalar(0,0,255),4);
cvLine(img, *pt[3], *pt[4], cvScalar(0,0,255),4);
cvLine(img, *pt[4], *pt[5], cvScalar(0,0,255),4);
cvLine(img, *pt[5], *pt[6], cvScalar(0,0,255),4);
cvLine(img, *pt[6], *pt[0], cvScalar(0,0,255),4);
}

//obtain the next contour
contours = contours->h_next;
}
// apply hough circles to find circles and draw a cirlce around it
cvCanny(imgGrayScale,imgCanny,0,0,3);
CvSeq* circles = cvHoughCircles(imgCanny,
storage,
CV_HOUGH_GRADIENT,
2,
imgCanny->height/4,
200,
100 );

for (int i = 0; i < circles->total; i++)
{
float* p = (float*)cvGetSeqElem( circles, i );
cvCircle( img, cvPoint(cvRound(p[0]),cvRound(p[1])),
3, CV_RGB(0,255,0), -1, 8, 0 );
cvCircle( img, cvPoint(cvRound(p[0]),cvRound(p[1])),
cvRound(p[2]), CV_RGB(0,255,255), 3, 8, 0 );
}
//show the image in which identified shapes are marked
cvNamedWindow("Tracked");
cvShowImage("Tracked",img);

cvWaitKey(0); //wait for a key press

//cleaning up
cvDestroyAllWindows();
cvReleaseMemStorage(&storage);
cvReleaseImage(&img);
cvReleaseImage(&imgGrayScale);

return 0;
}

вот ссылка на входное изображение
http://postimage.org/image/fmntii9lb/

и еще одна ссылка для вывода
http://postimage.org/image/4yhodbypj/

Мой вопрос: как решить те 2 (может быть, больше) ненужных больших круга в середине, которые всегда появляются, когда в кадре много фигур, заранее спасибо