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Java implementation of OpenCV Hough Circle Transform.
You can detect circles in a given image using the Hough circle transform. You can apply Hough Circle transform using the HoughCircles() method, this method accept the following parameters −
A Mat object representing the input image.
A Mat object to store the output vectors of the found circles.
An integers variables representing the detection method.
Two double variables representing an inverse ratio of the accumulator resolution to the image resolution and minimum distance between the centers of the detected circles.
Example
import org.opencv.core.Core;
import org.opencv.core.Mat;
import org.opencv.core.Point;
import org.opencv.core.Scalar;
import org.opencv.highgui.HighGui;
import org.opencv.imgcodecs.Imgcodecs;
import org.opencv.imgproc.Imgproc;
import java.awt.Image;
import java.awt.image.BufferedImage;
import java.io.IOException;
import javafx.application.Application;
import javafx.embed.swing.SwingFXUtils;
import javafx.scene.Group;
import javafx.scene.Scene;
import javafx.scene.image.ImageView;
import javafx.scene.image.WritableImage;
import javafx.stage.Stage;
public class HoughCircleTransform extends Application {
public void start(Stage stage) throws IOException {
//Loading the OpenCV core library
System.loadLibrary( Core.NATIVE_LIBRARY_NAME );
String file ="D:\Images\compass.jpg";
Mat src = Imgcodecs.imread(file);
//Converting the image to Gray
Mat gray = new Mat();
Imgproc.cvtColor(src, gray, Imgproc.COLOR_RGBA2GRAY);
//Blurring the image
Mat blur = new Mat();
Imgproc.medianBlur(gray, blur, 5);
//Detecting the Hough Circles
Mat circles = new Mat();
Imgproc.HoughCircles(blur, circles, Imgproc.HOUGH_GRADIENT, Math.PI/180, 150);
for (int i = 0; i < circles.cols(); i++ ) {
double[] data = circles.get(0, i);
Point center = new Point(Math.round(data[0]), Math.round(data[1]));
// circle center
Imgproc.circle(src, center, 1, new Scalar(0, 0, 255), 3, 8, 0 );
// circle outline
int radius = (int) Math.round(data[2]);
Imgproc.circle(src, center, radius, new Scalar(0,0,255), 3, 8, 0 );
}
//Converting matrix to JavaFX writable image
Image img = HighGui.toBufferedImage(src);
WritableImage writableImage= SwingFXUtils.toFXImage((BufferedImage) img, null);
//Setting the image view
ImageView imageView = new ImageView(writableImage);
imageView.setX(10);
imageView.setY(10);
imageView.setFitWidth(575);
imageView.setPreserveRatio(true);
//Setting the Scene object
Group root = new Group(imageView);
Scene scene = new Scene(root, 595, 400);
stage.setTitle("Hough Circle Transform");
stage.setScene(scene);
stage.show();
}
public static void main(String args[]) {
launch(args);
}
}Input Image
Output
On executing, the above produces the following output −
Updated on: 13-Apr-2020
504 Views
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