OpenCV - Drawing Arrowed Lines


You can draw an arrowed line on an image using the method arrowedLine() of the imgproc class. Following is the syntax of this method −

arrowedLine(Mat img, Point pt1, Point pt2, Scalar color)

This method accepts the following parameters −

  • mat − A Mat object representing the image on which the arrowed line is to be drawn.

  • pt1 and pt2 − Two Point objects representing the points between which the arrowed line is to be drawn.

  • scalar − A Scalar object representing the color of the arrowed line. (BGR)


The following program demonstrates how to draw arrowed line on an image and display it using JavaFX window.

import java.awt.image.BufferedImage;

import javax.imageio.ImageIO;

import javafx.application.Application;
import javafx.embed.swing.SwingFXUtils;
import javafx.scene.Group;
import javafx.scene.Scene;
import javafx.scene.image.ImageView;
import javafx.scene.image.WritableImage;
import javafx.stage.Stage;

import org.opencv.core.Core;
import org.opencv.core.Mat;
import org.opencv.core.MatOfByte;
import org.opencv.core.Point;
import org.opencv.core.Scalar;
import org.opencv.imgcodecs.Imgcodecs;
import org.opencv.imgproc.Imgproc;

public class DrawingArrowedLine extends Application {
   Mat matrix = null;

   public void start(Stage stage) throws Exception {
      // Capturing the snapshot from the camera
      DrawingArrowedLine obj = new DrawingArrowedLine();
      WritableImage writableImage = obj.LoadImage();

      // Setting the image view
      ImageView imageView = new ImageView(writableImage);

      // setting the fit height and width of the image view

      // Setting the preserve ratio of the image view

      // Creating a Group object
      Group root = new Group(imageView);

      // Creating a scene object
      Scene scene = new Scene(root, 600, 400);

      // Setting title to the Stage
      stage.setTitle("Drawing a line on the image");

      // Adding scene to the stage

      // Displaying the contents of the stage;
   public WritableImage LoadImage() throws Exception {
      // Loading the OpenCV core library
      System.loadLibrary( Core.NATIVE_LIBRARY_NAME );

      // Reading the Image from the file and storing it in to a Matrix object
      String file ="C:/EXAMPLES/OpenCV/Aish.jpg";
      Mat matrix = Imgcodecs.imread(file);

      //Drawing a line
         matrix,                       // Matrix obj of the image
         new Point(10, 200),           // p1
         new Point(590, 200),          // p2
         new Scalar(0, 100, 255)       // Scalar object for color

      // arrowedLine(Mat img, Point pt1, Point pt2, Scalar color)
      // Encoding the image
      MatOfByte matOfByte = new MatOfByte();
      Imgcodecs.imencode(".jpg", matrix, matOfByte);

      // Storing the encoded Mat in a byte array
      byte[] byteArray = matOfByte.toArray();

      // Displaying the image
      InputStream in = new ByteArrayInputStream(byteArray);
      BufferedImage bufImage =;
      this.matrix = matrix;

      // Creating the Writable Image
      WritableImage writableImage = SwingFXUtils.toFXImage(bufImage, null);

      return writableImage;
   public static void main(String args[]) {

On executing the above program, you will get the following output −

Drawing Arrowed Lines