Hough transformation for iris detection in OpenCV

I wrote the code for hough transformation and it works well. Also I can crop the eye location of a face. Now I want to detect the iris of the crop image with applying the Hough transfor开发者_如何学编程mation(cvHoughCircle). However when I try this procedure, the system is not able to find any circle on the image.

Maybe, the reason is, there are noises in the image but I don't think it's the reason. So, how can I detect the iris? I have the code of binary thresholding maybe I can use it, but I don't know how to do?

If anyone helps I really appreciate it. thx :)

You say that with binary thresold you get an iris that is pure white : that is not what you want to have. Use something like cvCanny in order to get only the edge of the iris.

Are you detecting the edges correctly?
Can you display the binary image and see the iris clearly?

circular hough transforms normally have a radius window (otherwise you are searching a 3d solution space) are you setting the window to a reasonable value?

void houghcircle()
{
    //cvSmooth( graybin,graybin, CV_GAUSSIAN, 5,5 );
    CvMemStorage* storage = cvCreateMemStorage(0);

    // smooth it, otherwise a lot of false circles may be detected
    CvSeq* circles = cvHoughCircles( edge, storage, CV_HOUGH_GRADIENT, 5, edge->height/4,1,1,2,50, 70 );
    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, 2, 0 );
        cvCircle( img, cvPoint(cvRound(p[0]),cvRound(p[1])), cvRound(p[2]), CV_RGB(255,0,0), 1, 2, 0 );
        cvNamedWindow( "circles", 1 );
        cvShowImage( "circles", img );
        cvWaitKey();
    }
}