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).

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 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;       Imgproc.circle (src, center, radius, color, thickness);       //Saving and displaying the image       Imgcodecs.imwrite("circle.jpg", src);       HighGui.imshow("Drawing a Circle", src);       HighGui.waitKey();    } }

Output

On executing, the above program generates the following window −