public Mat onCameraFrame(CvCameraViewFrame inputFrame) {
            Mat lowerRed = new Mat();
            Mat upperRed = new Mat();
            Mat redHueImage = new Mat();
            Mat green = new Mat();
            Mat greenHueImage = new Mat();
            Mat blue = new Mat();
            Mat blueHueImage = new Mat();
            Mat orange;

            Mat rgba = inputFrame.rgba();
            //Core.flip(rgba, rgba, 1);
            Mat HSVMat = new Mat();
            Imgproc.medianBlur(rgba,rgba,3);
            Imgproc.cvtColor(rgba, HSVMat, Imgproc.COLOR_RGB2HSV, 0);
    //detect red cirlces
            Core.inRange(HSVMat,new Scalar(0,70,100),new Scalar(10,255,255),lowerRed);
            Core.inRange(HSVMat,new Scalar(160,70,50),new Scalar(180,255,255),upperRed);
            Core.addWeighted(lowerRed,1.0,upperRed,1.0,0.0,redHueImage);
    //add green circles to red
            Core.inRange(HSVMat,new Scalar(50,100,100),new Scalar(70,255,255),green);
            Core.addWeighted(redHueImage,1.0,green,1.0,0.0,greenHueImage);
    //add blue circles to red and green
            Core.inRange(HSVMat,new Scalar(240,100,100),new Scalar(260,255,255),blue);
            Core.addWeighted(greenHueImage,1.0,blue,1.0,0.0,blueHueImage);

            Imgproc.GaussianBlur(blueHueImage, blueHueImage, new Size(9, 9), 2, 2);
            double dp = 1.2d;
            double minDist = 100;
            int minRadius = 30;
            int maxRadius = 100;
            double param1 = 70, param2 = 72;
            Mat circles = new Mat();


            Imgproc.HoughCircles(blueHueImage, circles, Imgproc.HOUGH_GRADIENT, dp, redHueImage.rows()/8, param1, param2, minRadius, maxRadius);
            int numCircles = (circles.rows() == 0) ? 0 : circles.cols();
            for (int i = 0; i < numCircles; i++) {
                double[] circleCoordinates = circles.get(0, i);
                int x = (int) circleCoordinates[0], y = (int) circleCoordinates[1];
                Point center = new Point(x, y);
                int radius = (int) circleCoordinates[2];
                Imgproc.circle(rgba, center, radius, new Scalar(0, 255, 0), 4);
            }
            circles.release();
            lowerRed.release();
            upperRed.release();
            HSVMat.release();
            redHueImage.release();

            return rgba;
        }