How to draw a circle in OpenCV using Java?

The org.opencv.imgproc package of Java OpenCV library contains a class named Imgproc.

To draw a circle you need to invoke the circle() method of this class. This method accepts the following parameters −

  • A Mat object representing the image on which the circle is to be drawn.

  • A Point object representing the center of the circle.

  • An integer variable representing the radius of the circle.

  • A Scalar object representing the color of the circle(BGR).

  • An integer representing the thickness of the circle(default 1).


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;
public class DrawingCircle {
   public static void main(String args[]) {
      //Loading the OpenCV core library
      System.loadLibrary( Core.NATIVE_LIBRARY_NAME );
      //Reading the source image in to a Mat object
      String file ="D:\images\blank.jpg";
      Mat src = Imgcodecs.imread(file);
      //Drawing a Circle
      Point center = new Point(300, 200);
      int radius = 100;
      Scalar color = new Scalar(64, 64, 64);
      int thickness = 10; (src, center, radius, color, thickness);
      //Saving and displaying the image
      Imgcodecs.imwrite("circle.jpg", src);
      HighGui.imshow("Drawing a Circle", src);


On executing, the above program generates the following window −