private void openImageButtonActionPerformed(java.awt.event.ActionEvent evt) {                                                
        try {
            fileOpen();
        } catch (IOException ex) {
            Logger.getLogger(NewJFrame.class.getName()).log(Level.SEVERE, null, ex);
        }

        if (JPanelImageArea != null) {
            this.remove(JPanelImageArea);
        }

        JPanelImageArea = new JPanel();
        JPanelImageArea.setBounds(10, 6, 701, 300);
        add(JPanelImageArea);

        if (originalImage.getWidth(null) < 700 || originalImage.getHeight(null) < 300) {
            imgViewer = new ImgViewer(originalImage, new Dimension(originalImage.getWidth(this), originalImage.getHeight(this)));
            JPanelImageArea.add(imgViewer);
            imgViewer.repaint();
        } else {
            imgScaleViewer = new ImgScaleViewer(originalImage, new Dimension(originalImage.getWidth(this), originalImage.getHeight(this)));
            JPanelImageArea.add(imgScaleViewer);
            imgViewer.repaint();
        }

        JPanelImageArea.repaint();
        JPanelImageArea.doLayout();
        JPanelTextArea.repaint();
        JPanelTextArea.doLayout();

    }                                               

import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Image;
import javax.swing.JPanel;

public class ImgViewer extends JPanel
{

    public ImgViewer(Image img, Dimension dim)
    {
    image = img;
    dimMinSize = dim;
    }    
    
    @Override
    public void paint(Graphics g) { 
        super.paintChildren(g);
        super.paintBorder(g);
        super.paintComponents(g);
        int x = (this.getWidth() - image.getWidth(null)) / 2;
        int y = (this.getHeight() - image.getHeight(null)) / 2;
        g.drawImage(image, x, y, this);
    }
           
    @Override
        public Dimension getPreferredSize()
    {
        return dimMinSize;
    }
    
    @Override
        public Dimension getMinimumSize()
    {
        return dimMinSize;
    }
    
    @Override
        public Dimension preferredSize()
    {
        return dimMinSize;
    }
    
    @Override
        public Dimension minimumSize()
    {
        return dimMinSize;
    }
    
    Image image;
    Dimension dimMinSize;
}