Grabbing Pixels from an image into an array

Question

Hi,
I am new to the image processing using java. I want to get the pixel values of an image and store it into an text file. Can anyone help me with this?
This is what i've done yet? Is the values present in the text field the correct values of the pixels of the image.
import java.awt.*;
import java.awt.image.*;
import java.applet.*;
import java.util.*;
public class grabber extends Applet {
private TextField tf;
private TextArea ta;
private Label status;
private Canvas drawarea;
private Image img=null;
int ppmline=0;
public void init() {
     setLayout(new GridLayout(1,2));
     Panel left=new Panel();
left.setLayout(new BorderLayout());
Panel topleft = new Panel();
topleft.setLayout(new GridLayout(1, 4));
topleft.add(tf=new TextField());
     Panel buttonsP = new Panel();
buttonsP.add(new Button("Load GIF"));
     buttonsP.add(new Button("PPM Output"));
     topleft.add(buttonsP);
left.add("North", topleft);
left.add("Center", drawarea=new Canvas());
     left.add("South", status=new Label());
     add(left);               // left side of the applet.
     add(ta=new TextArea());          // right side.
     status.setText("See GIF files below.");
public void paint(Graphics appletg) {
     Graphics g=drawarea.getGraphics();
     if (img != null) {
          g.drawImage(img, 0, 0, this);
          g.dispose();
public boolean action(Event evt, Object arg) {
     String s=(String) arg;
     if(s.equals("Load GIF")) {
          img=getImage(getCodeBase(), tf.getText());
          repaint();
     else if (s.equals("PPM Output")) getPixs();
return true;
void getPixs() {
     int w=30, h=30;
     // PPM output starts.
     ta.setText("P3\n");
     ta.appendText(Integer.toString(w) + " " + Integer.toString(h) + "\n");
     ta.appendText("255\n");
     handlepixels(img, 0, 0, w, h);
public void handlesinglepixel(int x, int y, int pixel) {
     // pixel is in RGB model. It is a 4-byte long integer.
     // It is converted into the string representation of PPM pixels.
     // ie. Hex 0x00102030 becomes "16 32 48"
     String s= Integer.toString((pixel & 0x00FF0000) >> 16) + " "
          + Integer.toString((pixel & 0x0000FF00) >> 8) + " "
          + Integer.toString(pixel & 0x000000FF) + " ";
// If we use PPM RAW format, then we have to use ascii characters instead.
//     char c[]= {(char) ((pixel & 0x00FF0000) >> 16),
//          (char) ((pixel & 0x0000FF00) >> 8) ,
//          (char) (pixel & 0x000000FF) };
//     String s=new String(c);
     if (ppmline++>=3) {                // comment out if you use RAW format.
          ta.appendText(s + "\n");      // comment out if you use RAW format.
          ppmline=0;               // comment out if you use RAW format.
     } else                          // comment out if you use RAW format.
          ta.appendText(s);
public void handlepixels(Image img, int x, int y, int w, int h) {
int[] pixels = new int[w * h];
PixelGrabber pg = new PixelGrabber(img, x, y, w, h, pixels, 0, w);
try {
pg.grabPixels();
} catch (InterruptedException e) {
System.err.println("interrupted waiting for pixels!");
return;
if ((pg.status() & ImageObserver.ABORT) != 0) {
System.err.println("image fetch aborted or errored");
return;
for (int j = 0; j < h; j++) {
for (int i = 0; i < w; i++) {
handlesinglepixel(x+i, y+j, pixels[j * w + i]);

Answer 1

im not at home or id post some source code but first off
if your going to write a file from a applet your going to
have to get by permisions.
so you should probably do this with a application
it would be alot easier
use toolkit.getdefaulttoolkit() to get the image then
use the pixel graber class to read it into a array
of the type you want string or char
then just write it into a file each element of the array
and when you want to read it just read it in with file reader
you could probaly do a test run just write in each value as
a string and put a comma between each value then use
stringtokenizer to read it back in its less efficient but
for a test run it would make things clearer
sorry if its not much help