How to reset JFrame in java

I am a beginner to java. I have ImageFrame class as follows: ``` public class ImageFrame extends JFrame { private static final long serialVersionUID = 1L; public static final int DEFAULT_WIDTH = 1365; public static final int DEFAULT_HEIGHT = 730; GettingImage getimg = new GettingImage(); private BufferedImage image = getimg.getImage(); final ImageProcessing operation = new ImageProcessing(image); public ImageFrame(){ setTitle("ImageTest"); setSize(DEFAULT_WIDTH, DEFAULT_HEIGHT); JMenu process = new JMenu("Process"); JMenuItem greyscale = new JMenuItem("greyscale"); process.add(greyscale); //adding action listener to menu items greyscale.addActionListener( new ActionListener(){ public void actionPerformed(ActionEvent e) { image = operation.greyscale(); System.out.println("greyscale is pressed"); } } ); JMenuBar bar = new JMenuBar(); setJMenuBar(bar); bar.add(process); setSize(1365, 730); setVisible(true); ImageComponent component = new ImageComponent(image); add(component); } } ``` But the image is not converted into greyscale when I press the greyscale submenu but when I minimized the window and maximize it then the image is changed into greyscale. I think it is due to the fact that the window is not refreshed. How do I refresh it?