How to draw an ellipse in OpenCV using Java?

The org.opencv.imgproc package of Java OpenCV library contains a class named Imgproc. To draw an ellipse you need to invoke the ellipse() method of this class. This method accepts the following parameters −

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

  • A RotatedRect object (The ellipse is drawn inscribed in this rectangle.)

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

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


import org.opencv.core.Core;
import org.opencv.core.Mat;
import org.opencv.core.Point;
import org.opencv.core.RotatedRect;
import org.opencv.core.Scalar;
import org.opencv.core.Size;
import org.opencv.highgui.HighGui;
import org.opencv.imgcodecs.Imgcodecs;
import org.opencv.imgproc.Imgproc;
public class DrawingEllipse {
   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
      Mat src = Imgcodecs.imread("D:\images\blank.jpg");
      //Drawing an Ellipse
      RotatedRect box = new RotatedRect(new Point(300, 200), new Size(260, 180), 180);
      Scalar color = new Scalar(64, 64, 64);
      int thickness = 10;
      Imgproc.ellipse (src, box, color, thickness);
      //Saving and displaying the image
      Imgcodecs.imwrite("arrowed_line.jpg", src);
      HighGui.imshow("Drawing an ellipse", src);


On executing, the above program generates the following window −