Explain OpenCV Laplacian Transformation using java Example

The Laplacian transform on an image highlights the regions where there is a rapid intensity change. Therefore, it is used to detect edges.

The Laplacian() method of the Imgproc class applies Laplacian Transform on the given image, this method accepts −

• Two Mat objects representing the source and destination images.

• Four integer variables representing the depth, size, scale and, delta values of the transform.

• An integer value representing the border.

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.CvType;
import org.opencv.core.Mat;
import org.opencv.highgui.HighGui;
import org.opencv.imgcodecs.Imgcodecs;
import org.opencv.imgproc.Imgproc;
public class LaplacianTransform extends Application {
   public void start(Stage stage) throws IOException {
      //Loading OpenCV library
      System.loadLibrary(Core.NATIVE_LIBRARY_NAME);
      //Creating Mat objects to store source and destination images
      Mat src = new Mat();
      Mat dst = new Mat();
      //Reading Image
      src = Imgcodecs.imread("D:\Images\road3.jpg");
      //Applying Laplacian transform
      Imgproc.Laplacian( src, dst, CvType.CV_16S, 3, 1, 0, Core.BORDER_DEFAULT );
      //Imgproc.Laplacian(src, dst, ddepth, ksize, scale, delta, borderType);
      // converting back to CV_8U
      Core.convertScaleAbs( dst, dst );
      //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("Laplacian Transform");
      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 −

Maruthi Krishna

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Updated on: 13-Apr-2020

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