How to rotate an image with OpenCV using Java?

The warpAffine() method of the Imgproc class applies an affine transformation to the specified image. This method accepts −

• Three Mat objects representing the source, destination, and transformation matrices.

• An integer value representing the size of the output image.

To rotate an image Create a rotation matrix and pass it as a transformation matrix to this method along with the other parameters.

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.core.Point;
import org.opencv.core.Size;
import org.opencv.highgui.HighGui;
import org.opencv.imgcodecs.Imgcodecs;
import org.opencv.imgproc.Imgproc;
public class RotatingAnImage extends Application {
   public void start(Stage stage) throws IOException {
      //Loading the OpenCV core library
      System.loadLibrary( Core.NATIVE_LIBRARY_NAME );
      //Reading image data
      String file ="D:\Images\elephant.jpg";
      Mat src = Imgcodecs.imread(file);
      //Creating destination matrix
      Mat dst = new Mat(src.rows(), src.cols(), src.type());
      // Creating a Point object
      Point point = new Point(300, 200);
      //Creating the transformation matrix
      Mat rotationMatrix = Imgproc.getRotationMatrix2D(point, 30, 1);
      // Creating the object of the class Size
      Size size = new Size(src.cols(), src.cols());
      // Rotating the given image
      Imgproc.warpAffine(src, dst, rotationMatrix, size);
      //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("Image Rotation Example");
      stage.setScene(scene);
      stage.show();
   }
   public static void main(String args[]) {
      launch(args);
   }
}

Input Image

Output

On executing the above program, it generates the following output −