How to draw a filled circle in OpenCV using Java?

JavaObject Oriented ProgrammingProgramming

The org.opencv.imgproc package of Java OpenCV library contains a class named Imgproc. This class provides a method named circle(), using this you can draw a circle on an image. This method provides 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).

If you pass Imgproc.FILLEDas line type, this method generates/draws a filled circle.

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;
public class DrawingFilledCircle {
   public static void main(String args[]) {
      //Loading the OpenCV core library
      System.loadLibrary( Core.NATIVE_LIBRARY_NAME );
      //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 a Circle
      Point center = new Point(300, 200);
      int radius =100;
      Scalar color = new Scalar(64, 64, 64);
      int thickness = Imgproc.FILLED;
      Imgproc.circle (src, center, radius, color, thickness);
      //Saving and displaying the image
      Imgcodecs.imwrite("arrowed_line.jpg", src);
      HighGui.imshow("Drawing a circle", src);
      HighGui.waitKey();
   }
}

Output

On executing, the above program generates the following window −

raja
Published on 10-Apr-2020 07:48:12
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