Hough circle detection android

Question

I am trying to detect circles using android. I managed to implement a line detection algorithm, but when I try to draw circles hough circles nothing is displayed.

Here is my code:

Mat thresholdImage = new Mat(getFrameHeight() + getFrameHeight() / 2, getFrameWidth(), CvType.CV_8UC1); mYuv.put(0, 0, data); Imgproc.cvtColor(mYuv, destination, Imgproc.COLOR_YUV420sp2RGB, 4); Imgproc.cvtColor(destination, thresholdImage, Imgproc.COLOR_RGB2GRAY, 4); Imgproc.GaussianBlur(thresholdImage, thresholdImage, new Size(9, 9), 2, 2 ); Mat circles = new Mat(); Imgproc.HoughCircles(thresholdImage, circles, Imgproc.CV_HOUGH_GRADIENT, 1d, (double)thresholdImage.height()/70, 200d, 100d); Log.w("circles", circles.cols()+""); for (int x = 0; x < circles.cols(); x++) { double vCircle[]=circles.get(0,x); Point center=new Point(Math.round(vCircle[0]), Math.round(vCircle[1])); int radius = (int)Math.round(vCircle[2]); // draw the circle center Core.circle(destination, center, 3,new Scalar(0,255,0), -1, 8, 0 ); // draw the circle outline Core.circle( destination, center, radius, new Scalar(0,0,255), 3, 8, 0 ); } 

Answer 1

You may have already been sorted, but a few things. I would check that your circles have actual results; sometimes vCircle seems to return zero; try one of the other versions of HoughCircles:

 iCannyUpperThreshold = 100; iMinRadius = 20; iMaxRadius = 400; iAccumulator = 300; Imgproc.HoughCircles(thresholdImage, circles, Imgproc.CV_HOUGH_GRADIENT, 2.0, thresholdImage.rows() / 8, iCannyUpperThreshold, iAccumulator, iMinRadius, iMaxRadius); if (circles.cols() > 0) for (int x = 0; x < circles.cols(); x++) { 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 Core.circle(destination, pt, radius, new Scalar(0,255,0), iLineThickness); Core.circle(destination, pt, 3, new Scalar(0,0,255), iLineThickness); } 

(I changed my code to my own, renamed it to some material and changed it back, I think I returned it to make it work ...)

IN.