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 :)

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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.

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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?

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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();
    }
}