Currently I am developing an app, which will detect circles from photos. I have managed to write a code for this, but through some testing I noticed that it has trouble recognizing shape if I move phone away a bit. Can I somehow improve the result? Because I have seen as way smaller circles were detected in other peoples programs. Also I need my app to recon only 9 circles, which it does if I have more, but if the amount is smaller it crashes.
Here's my detection code:
Mat mat = new Mat(bitmap.getWidth(), bitmap.getHeight(),
CvType.CV_8UC1);
Mat grayMat = new Mat(bitmap.getWidth(), bitmap.getHeight(),
CvType.CV_8UC1);
Utils.bitmapToMat(bitmap, mat);
int colorChannels = (mat.channels() == 3) ? Imgproc.COLOR_BGR2GRAY
: ((mat.channels() == 4) ? Imgproc.COLOR_BGRA2GRAY : 1);
Imgproc.cvtColor(mat, grayMat, colorChannels);
Imgproc.GaussianBlur(grayMat, grayMat, new Size(9, 9), 2, 2);
// accumulator value
double dp = 1.2d;
// minimum distance between the center coordinates of detected circles in pixels
double minDist = 100;
int minRadius = 0, maxRadius = 0;
double param1 = 70, param2 = 72;
Mat circles = new Mat(bitmap.getWidth(),
bitmap.getHeight(), CvType.CV_8UC1);
Imgproc.HoughCircles(grayMat, circles,
Imgproc.CV_HOUGH_GRADIENT, dp, minDist, param1,
param2, minRadius, maxRadius);
int numberOfCircles = 9;
for (int i=0; i<numberOfCircles; i++) {
double[] circleCoordinates = circles.get(0, i);
int x = (int) circleCoordinates[0], y = (int) circleCoordinates[1];
Point center = new Point(x, y);
android.graphics.Point centerC = new android.graphics.Point(x, y);
int radius = (int) circleCoordinates[2];
Core.circle(mat, center, radius, new Scalar(0,
255, 0), 4);
Core.rectangle(mat, new Point(x - 5, y - 5),
new Point(x + 5, y + 5),
new Scalar(0, 128, 255), -1);
Thanks in advance.