You can add borders to a given image using the copyMakeBorder() method, this method accepts the following parameters −
Two Mat objects representing the source and destination images.
An object of the class Mat representing the destination (output) image.
Four integer variables representing the lengths of the borders in all the 4 directions of the image.
An integer variable representing the type of the border that is to be used.
Example
import java.awt.Image;
import java.awt.image.BufferedImage;
import java.io.IOException;
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.highgui.HighGui;
import org.opencv.imgcodecs.Imgcodecs;
public class AddingBorders extends Application {
public void start(Stage stage) throws IOException {
//Loading the OpenCV core library
System.loadLibrary( Core.NATIVE_LIBRARY_NAME );
String file ="D:\\Images\\cat.jpg";
Mat src = Imgcodecs.imread(file);
//Creating an empty matrices to store the destination image.
Mat dst = new Mat(src.rows(), src.cols(), src.type());
//Adding borders
Core.copyMakeBorder(src, dst, 20, 20, 20, 20, Core.BORDER_CONSTANT);
//Converting matrix to JavaFX writable image
Image img = HighGui.toBufferedImage(dst);
WritableImage writableImage= SwingFXUtils.toFXImage((BufferedImage) img, null);
//Setting the image view
ImageView imageView = new ImageView(writableImage);
imageView.setX(10);
imageView.setY(10);
imageView.setFitWidth(575);
imageView.setPreserveRatio(true);
//Setting the Scene object
Group root = new Group(imageView);
Scene scene = new Scene(root, 595, 400);
stage.setTitle("Adding Borders");
stage.setScene(scene);
stage.show();
}
public static void main(String args[]) {
launch(args);
}
}Input Image
Output
On executing, the above program generates the following windows −
