Java Code Examples for org.opencv.imgproc.Imgproc#HoughCircles

@Override
public Mat onCameraFrame(CameraBridgeViewBase.CvCameraViewFrame inputFrame) {
    Mat input = inputFrame.gray();
    Mat circles = new Mat();
    Imgproc.blur(input, input, new Size(7, 7), new Point(2, 2));
    Imgproc.HoughCircles(input, circles, Imgproc.CV_HOUGH_GRADIENT, 2, 100, 100, 90, 0, 1000);

    Log.i(TAG, String.valueOf("size: " + circles.cols()) + ", " + String.valueOf(circles.rows()));

    if (circles.cols() > 0) {
        for (int x=0; x < Math.min(circles.cols(), 5); x++ ) {
            double circleVec[] = circles.get(0, x);

            if (circleVec == null) {
                break;
            }

            Point center = new Point((int) circleVec[0], (int) circleVec[1]);
            int radius = (int) circleVec[2];

            Imgproc.circle(input, center, 3, new Scalar(255, 255, 255), 5);
            Imgproc.circle(input, center, radius, new Scalar(255, 255, 255), 2);
        }
    }

    circles.release();
    input.release();
    return inputFrame.rgba();
}
 

void HoughCircles() {
    Mat grayMat = new Mat();
    Mat cannyEdges = new Mat();
    Mat circles = new Mat();

    //Converting the image to grayscale
    Imgproc.cvtColor(originalMat, grayMat, Imgproc.COLOR_BGR2GRAY);

    Imgproc.Canny(grayMat, cannyEdges, 10, 100);

    Imgproc.HoughCircles(cannyEdges, circles, Imgproc.CV_HOUGH_GRADIENT, 1, cannyEdges.rows() / 15);//, grayMat.rows() / 8);

    Mat houghCircles = new Mat();
    houghCircles.create(cannyEdges.rows(), cannyEdges.cols(), CvType.CV_8UC1);

    //Drawing lines on the image
    for (int i = 0; i < circles.cols(); i++) {
        double[] parameters = circles.get(0, i);
        double x, y;
        int r;

        x = parameters[0];
        y = parameters[1];
        r = (int) parameters[2];

        Point center = new Point(x, y);

        //Drawing circles on an image
        Imgproc.circle(houghCircles, center, r, new Scalar(255, 0, 0), 1);
    }

    //Converting Mat back to Bitmap
    Utils.matToBitmap(houghCircles, currentBitmap);
    imageView.setImageBitmap(currentBitmap);
}
 

public static void main (String[] args) {
		CVLoader.load();
		Mat orig = Highgui.imread("data/topdown-6.jpg");
		Mat gray = new Mat();
		orig.copyTo(gray);
		
		// blur
//		Imgproc.medianBlur(gray, gray, 5);
//		Imgproc.GaussianBlur(gray, gray, new Size(3, 3), 100);
		
		// convert to grayscale
		Imgproc.cvtColor(gray, gray, Imgproc.COLOR_BGR2GRAY);
		
		// do hough circles
		Mat circles = new Mat();
		int minRadius = 10;
		int maxRadius = 18;
		Imgproc.HoughCircles(gray, circles, Imgproc.CV_HOUGH_GRADIENT, 1, minRadius, 120, 10, minRadius, maxRadius);
		System.out.println(circles);
		
		ImgWindow.newWindow(gray);
		ImgWindow wnd = ImgWindow.newWindow(orig);			
		
		while(!wnd.closed) {
			wnd.setImage(orig);
			Graphics2D g = wnd.begin();
			g.setColor(Color.MAGENTA);
			g.setStroke(new BasicStroke(3));
			for(int i = 0; i < circles.cols(); i++) {
				double[] circle = circles.get(0, i);
				g.drawOval((int)circle[0] - (int)circle[2], (int)circle[1] - (int)circle[2], (int)circle[2] * 2, (int)circle[2] * 2);
			}		
			wnd.end();
		}
	}
 

private void extractCircles (Mat mask, List<Circle> balls, List<BallCluster> ballClusters, List<MatOfPoint> contours) {
	// clear input
	balls.clear();
	ballClusters.clear();
	contours.clear();
	
	// find the contours
	Imgproc.findContours(mask.clone(), contours, new Mat(), Imgproc.RETR_LIST, Imgproc.CHAIN_APPROX_SIMPLE);
	
	// iterate through the contours, find single balls and clusters of balls touching each other
	double minArea = Math.PI * (calib.getBallRadius() * 0.9f) * (calib.getBallRadius() * 0.9f); // minimal ball area
	double maxArea = Math.PI * (calib.getBallRadius() * 1.1f) * (calib.getBallRadius() * 1.1f); // maximal ball area

	for (int i = 0; i < contours.size(); i++) {
		double area = Imgproc.contourArea(contours.get(i));
		if (area > minArea) {				
			if (area < maxArea) {
				// we found a ball
				float[] radius = new float[1];
				Point center = new Point();
				Imgproc.minEnclosingCircle(new MatOfPoint2f(contours.get(i).toArray()), center, radius);
				balls.add(new Circle(center.x, center.y, calib.getBallRadius()));
			} else {
				// we found a cluster of balls
				int numBalls = (int)(area / (Math.PI * calib.getBallRadius() * calib.getBallRadius() * 0.9));
				
				// draw the contours to a bit mask
				Mat hough = Mat.zeros(mask.size(), CvType.CV_8U);
				Imgproc.drawContours(hough, contours, i, new Scalar(255, 255, 255), -2);
				
				// detect hough circles, try different params until we hit the number of balls
				Mat houghCircles = new Mat();
				int hit = 0;
				for(int j = 8; j < 20; j++) {
					Imgproc.HoughCircles(hough, houghCircles, Imgproc.CV_HOUGH_GRADIENT, 2, calib.getBallRadius() * 0.9 * 2, 255, j, (int)(calib.getBallRadius() * 0.9), (int)(calib.getBallRadius() * 1.1));
					if(houghCircles.cols() <= numBalls) {
						hit++;
						if(hit == 4) break;
					}
				}
				
				
				List<Circle> estimatedCircles = new ArrayList<Circle>();
				for(int j = 0; j < houghCircles.cols(); j++) {
					double[] circle = houghCircles.get(0, j);
					if(circle != null) {
						estimatedCircles.add(new Circle(circle[0], circle[1], calib.getBallRadius()));
					}
				}
				
				ballClusters.add(new BallCluster(contours.get(i), numBalls, estimatedCircles));
			}
		}
	}
}