Best parameters for pupil detection using hough? java opencv

Question

--------------read edit below--------------- I am trying to detect the edge of the pupils and iris within various images. I am altering parameters and such but I can only manage to ever get one iris/pupil outline correct, or get unnecessary outlines in the background, or none at all. Is the some specific parameters that I should try to try and get the correct outlines. Or is there a way that I can crop the image just to the eyes, so the system can focus on that part?

This is my UPDATED method:

private void findPupilIris() throws IOException {
    //converts and saves image in grayscale

    Mat newimg = Imgcodecs.imread("/Users/.../pic.jpg");
    Mat des = new Mat(newimg.rows(), newimg.cols(), newimg.type());
    Mat norm = new Mat();

    Imgproc.cvtColor(newimg, des, Imgproc.COLOR_BGR2HSV);
    List<Mat> hsv = new ArrayList<Mat>();
    Core.split(des, hsv);
    Mat v = hsv.get(2); //gets the grey scale version

    Imgcodecs.imwrite("/Users/Lisa-Maria/Documents/CapturedImages/B&Wpic.jpg", v); //only writes mats

    CLAHE clahe = Imgproc.createCLAHE(2.0, new Size(8,8) ); //2.0, new Size(8,8) 
    clahe.apply(v,v);
//    Imgproc.GaussianBlur(v, v, new Size(9,9), 3); //adds left pupil boundary and random circle on 'a'
 //   Imgproc.GaussianBlur(v, v, new Size(9,9), 13); //adds right outer iris boundary and random circle on 'a'
    Imgproc.GaussianBlur(v, v, new Size(9,9), 7);  //adds left outer iris boundary and random circle on left by hair
  //  Imgproc.GaussianBlur(v, v, new Size(7,7), 15);
    Core.addWeighted(v, 1.5, v, -0.5, 0, v);


    Imgcodecs.imwrite("/Users/.../after.jpg", v); //only writes mats
    if (v != null) {
        Mat circles = new Mat();

        Imgproc.HoughCircles( v, circles, Imgproc.CV_HOUGH_GRADIENT, 2, v.rows(), 100, 20, 20, 200 );

        List<MatOfPoint> contours = new ArrayList<MatOfPoint>();

        System.out.println("circles.cols() " + circles.cols());
        if(circles.cols() > 0) {
            System.out.println("1");
            for (int x = 0; x < circles.cols(); x++) {
                System.out.println("2");
                double vCircle[] = circles.get(0, x);


                if(vCircle == null) {
                    break;
                }

                Point pt = new Point(Math.round(vCircle[0]), Math.round(vCircle[1]));
                int radius = (int) Math.round(vCircle[2]);

                //draw the found circle




                Imgproc.circle(v, pt, radius, new Scalar(255,0,0),2); //newimg
                //Imgproc.circle(des, pt, radius/3, new Scalar(225,0,0),2); //pupil
                Imgcodecs.imwrite("/Users/.../Houghpic.jpg", v); //newimg

                //draw the mask: white circle on black background
//                  Mat mask = new Mat( new Size( des.cols(), des.rows() ), CvType.CV_8UC1 );
//                  Imgproc.circle(mask, pt, radius, new Scalar(255,0,0),2); 

//                  des.copyTo(des,mask);
//                  Imgcodecs.imwrite("/Users/..../mask.jpg", des); //newimg


                Imgproc.logPolar(des, norm, pt, radius, Imgproc.WARP_FILL_OUTLIERS);
                Imgcodecs.imwrite("/Users/..../Normalised.jpg",norm);
            }
        }
    }
}

Result: hough pic

Answer 1

Following discussion in comments, I am posting a general answer with some results I got on the worst case image uploaded by the OP.

Note : The code I am posting is in Python, since it is the fastest for me to write

Step 1. As you ask for a way to crop the image, so as to focus on the eyes only, you might want to look at Face Detection. Since, the image essentially requires to find eyes only, I did the following:

eye_cascade = cv2.CascadeClassifier('haarcascade_eye.xml')
eyes = eye_cascade.detectMultiScale(v) // v is the value channel of the HSV image
// The results "eyes" gives you the dimensions of the rectangle where the eyes are detected as [x, y, w, h]
// Just for drawing 
cv2.rectangle(v, (x1, y1), (x1+w1, y1+h1), (0, 255, 0), 2)
cv2.rectangle(v, (x2, y2), (x2+w2, y2+h2), (0, 255, 0), 2)

Now, once you have the bounding rectangles, you can crop the rectangles from the image like:

crop_eye1 = v[y1:y1+h1, x1:x1+w1]
crop_eye2 = v[y2:y2+h2, x2:x2+w2]

After you obtain the rectangles, I would suggest looking into different color spaces instead of RGB/BGR, HSV/Lab/Luv in particular.

Because the R, G, and B components of an object’s color in a digital image are all correlated with the amount of light hitting the object, and therefore with each other, image descriptions in terms of those components make object discrimination difficult. Descriptions in terms of hue/lightness/chroma or hue/lightness/saturation are often more relevant

Then, once, you have the eyes, its time to equalize the contrast of the image, however, I suggest using CLAHE and play with the parameters for clipLimit and tileGridSize. Here is a code which I implemented a while back in Java:

private static Mat clahe(Mat image, int ClipLimit, Size size){
  CLAHE clahe = Imgproc.createCLAHE();
  clahe.setClipLimit(ClipLimit);
  clahe.setTilesGridSize(size);
  Mat dest_image = new Mat();
  clahe.apply(image, dest_image);
  return dest_image;
}     

Once you are satisfied, you should sharpen the image so that HoughCircle is robust. You should look at unsharpMask. Here is the code in Java for UnsharpMask I implemented in Java:

private static Mat unsharpMask(Mat input_image, Size size, double sigma){

// Make sure the {input_image} is gray.
  Mat sharpend_image = new Mat(input_image.rows(), input_image.cols(), input_image.type());
  Mat Blurred_image = new Mat(input_image.rows(), input_image.cols(), input_image.type());
  Imgproc.GaussianBlur(input_image, Blurred_image, size, sigma);
  Core.addWeighted(input_image, 2.0D, Blurred_image, -1.0D, 0.0D, sharpened_image);
  return sharpened_image;
}

Alternatively, you could use bilateral filter, which is edge preserving smoothing, or read through this for defining a custom kernel for sharpening image. Hope it helps and best of luck!