Apply effect of Glow on ImageView

javafx.scene.effect.Glow is a high-level effect that makes the input image appear to glow, based on a configurable threshold.

package javafx_imageprocessing;

import javafx.application.Application;
import javafx.event.ActionEvent;
import javafx.event.EventHandler;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.Slider;
import javafx.scene.control.SliderBuilder;
import javafx.scene.control.Tooltip;
import javafx.scene.effect.Glow;
import javafx.scene.image.Image;
import javafx.scene.image.ImageView;
import javafx.scene.layout.HBox;
import javafx.scene.layout.StackPane;
import javafx.scene.layout.VBox;
import javafx.stage.Stage;

/**
 *
 * @web http://java-buddy.blogspot.com/
 */
public class JavaFX_ImageProcessing extends Application {
    
    ImageView imageView_Source, imageView_Target;
    Slider sliderLevel;
    
    @Override
    public void start(Stage primaryStage) {
        
        Image image = new Image("http://goo.gl/kYEQl");
        imageView_Source = new ImageView();
        imageView_Source.setImage(image);

        imageView_Target = new ImageView();
        imageView_Target.setImage(image);
        
        HBox hBoxImage = new HBox();
        hBoxImage.getChildren().addAll(imageView_Source, imageView_Target);
        
        sliderLevel = SliderBuilder.create()
                .prefWidth(300)
                .min(0)
                .max(1)
                .majorTickUnit(0.2)
                .showTickMarks(true)
                .showTickLabels(true)
                .value(0.3)
                .tooltip(new Tooltip("Level"))
                .build();

        Button btnProcess = new Button("Process...");
        btnProcess.setOnAction(btnProcessEventListener);
        
        VBox vBox = new VBox();
        vBox.getChildren().addAll(hBoxImage, 
                sliderLevel, 
                btnProcess);
        
        StackPane root = new StackPane();
        root.getChildren().add(vBox);
        Scene scene = new Scene(root, 350, 330);
        primaryStage.setTitle("java-buddy.blogspot.com");
        primaryStage.setScene(scene);
        primaryStage.show();
        
        updateEffect();

    }

    public static void main(String[] args) {
        launch(args);
    }
    
    EventHandler<ActionEvent> btnProcessEventListener
    = new EventHandler<ActionEvent>(){

        @Override
        public void handle(ActionEvent t) {
            updateEffect();
        }
    };
    
    private void updateEffect(){
        Double valueLevel = sliderLevel.valueProperty().doubleValue(); 
        Glow glow = new Glow(valueLevel);
        imageView_Target.setEffect(glow);
    }
}