This won't compile.  BufferedImage.getScaledInstance() returns an Image.

I was expecting you to draw you image in Printable.print().  I haven't
played with document printing in this style before.  Try the little
program below.  Change the kittens.jpg to your own image and adjust the
PageFormat with the dialog.  This will print the image scaled to fit in
the imageable width.

import java.awt.*;
import java.awt.event.*;
import java.awt.image.*;
import java.awt.print.*;
import java.io.*;
import javax.imageio.*;
import javax.swing.*;

public class test extends JPanel implements Printable {
    BufferedImage bi;
    int w,h;
    volatile static PageFormat pf;

    public test() {
        try {
            bi = ImageIO.read(new File("kittens.jpg"));
            w = bi.getWidth();
            h = bi.getHeight();
            setPreferredSize(new Dimension(w,h));
        } catch (IOException ioe) {
            ioe.printStackTrace();
        }
    }

    void render(Graphics g, boolean printerFlag) {
        if (printerFlag)
            g.drawImage(bi,
             (int)pf.getImageableX(),
             (int)pf.getImageableY(),
             (int)pf.getImageableWidth(),
             (int)(pf.getImageableWidth()/1.333),null);
        else
            g.drawImage(bi,0,0,w,h,null);
    }

    public void paintComponent(Graphics g) {
        render(g, false);
    }

    public int print(Graphics g, PageFormat pageFormat, int pageIndex) {
        int retcod = Printable.PAGE_EXISTS;
        if (pageIndex == 0) {
            render(g, true);
        } else
            retcod = Printable.NO_SUCH_PAGE;

        return retcod;
    }

    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {
            public void run() {
                JFrame f = new JFrame("test");
                f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                final test t = new test();
                f.add(t,BorderLayout.CENTER);
                JButton b = new JButton("Print");
                b.addActionListener(new ActionListener() {
                    public void actionPerformed(ActionEvent ae) {
                        PrinterJob pj = PrinterJob.getPrinterJob();
                        pf = pj.defaultPage();
                        pj.setPrintable(t);
                        PageFormat pf = pj.pageDialog(pj.defaultPage());
                        try {
                            pj.print();
                        } catch (PrinterException pe) {
                            pe.printStackTrace();
                        }
                    }
                });
                f.add(b,BorderLayout.SOUTH);
                f.pack();
                f.setVisible(true);
            }
        });
    }
}

Oh and for a really good description of all the methods;

http://java.sun.com/j2se/1.4.2/docs/guide/jps/index.html