How to update a JScrollPane?

Hello!

I try to write a small Image viewer in Java where I should be able to view images and do some small adjustments.

When my app starts there should be no image loaded at all. But when I load it and the image is bigger then the JscrollPane I would like to have the scrolls. But in some how they will not be updated.

I use a ImagePanel of my own beacuse I need to do som adjustments. Se code below.

I create my JScrollPane like:
ImagePanel imagePanel = new ImagePanel();
JScrollPane jscrollPane = new JScrollPane(imagePanel, JScrollPane.VERTICAL_SCROLLBAR_AS_NEEDED, JScrollPane.HORIZONTAL_SCROLLBAR_AS_NEEDED);

I load a new Image like:
public void open()
{
    try
    {
        JFileChooser fileChooser = new JFileChooser(".");
        fileChooser.setDialogType(JFileChooser.OPEN_DIALOG);
        fileChooser.setMultiSelectionEnabled(false);

        if(JFileChooser.APPROVE_OPTION == fileChooser.showOpenDialog(this))
        {
            if(fileChooser.getSelectedFile() != null)
            {
                Image jpg = getToolkit().getImage(fileChooser.getSelectedFile().getPath());

                MediaTracker mediaTracker = new MediaTracker(this);
                try
                {
                    mediaTracker.addImage(jpg, 0);

                    mediaTracker.waitForID(0);
                }
                catch(InterruptedException ie)
                {
                }

                imagePanel = new ImagePanel(jpg);

                jscrollPane.setViewportView(imagePanel);

            }
        }
    }
    catch(Exception e)
    {
        e.printStackTrace();
    }
}

...But the scrollbars refuse to be updated.

So if any one know how to solve this. BTW I do have to use the ImagePanel!

Best regards
Fredrik

My code for the ImagePanel looks like:
import java.awt.*;
import java.applet.*;
import javax.swing.*;
import java.awt.image.*;

public class ImagePanel extends JPanel
{
    private Image jpg;
    private Image resultImage;

    private BleachFilter bleachFilter = new BleachFilter(1.5);
    private DarkFilter darkFilter = new DarkFilter(1.5);
    private NegativeFilter negativeFilter = new NegativeFilter();
    private int[] pixels = new int[300 * 300];

    public ImagePanel()
    {
        super();

        resultImage = null;
        jpg = null;
        setBackground(new Color(255, 255, 255));
    }

    public ImagePanel(Image j)
    {
        super();

        resultImage = j;
        jpg = j;
        setBackground(new Color(0, 0, 0));
        setSize(j.getWidth(this), j.getHeight(this));

        System.out.println(j.getWidth(this) + " " + j.getHeight(this));
    }

    public void paintComponent(Graphics g)
    {
        super.paintComponent(g);
        Graphics2D graphics2D = (Graphics2D)g;
        if(resultImage != null)
        {
            graphics2D.drawImage(resultImage, 0, 0, this);
        }
    }

    public void setFilter(int i)
    {
        if(i == 0)
        {
            resultImage = jpg;
        }
        if(i == 1)
        {
            ImageProducer imageProducer = new FilteredImageSource( jpg.getSource(), bleachFilter);
            resultImage = createImage(imageProducer);
        }
        else if(i == 2)
        {
            ImageProducer imageProducer = new FilteredImageSource( jpg.getSource(), darkFilter);
            resultImage = createImage(imageProducer);
        }
        else if(i == 3)
        {
            ImageProducer imageProducer = jpg.getSource();
            NegativeFilter negativeFilter = new NegativeFilter();
            FilteredImageSource filteredImageSource = new FilteredImageSource(imageProducer, negativeFilter);
            resultImage = createImage(filteredImageSource);
        }

        repaint();
    }
}