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 −
