PixelGrabber

Question

Hi all,
I'm using the method grabPixel of the class PixelGrabber to get an array of pixels of an image.
The problem is that the array I'm getting is not correct and the x right pixels(in my case 473 right pixels) in each line of the matrix of the image is shifted to the left part of that line and all of them get the value 0 (which is black).
How can I avoid this problem?
The following code is the code of the class using PixelGrabber:
import javax.swing.*;
import java.io.*;
import java.awt.*;
import java.awt.event.*;
import java.net.*;
import java.awt.image.*;
public class FilePanel extends JPanel {
protected Image currentImage = null, modImg = null;
private boolean isFile = false;
private int pictureWidth, pictureHeight;
private int count = 0;
protected int[] pixels, pix;
private MediaTracker tracker;
private ColorModel colorModel;
public FilePanel() {
setBorder (BorderFactory.createTitledBorder("Picture Area:"));
tracker = new MediaTracker(this);
colorModel = ColorModel.getRGBdefault();
public void setFile(String fileName)
if (fileName != null)
currentImage=null;
isFile = true;
if (fileName.endsWith(".bmp") || fileName.endsWith(".BMP"))
BMP bmp = new BMP(new java.io.File(fileName));
currentImage = bmp.getImage();
else
Toolkit toolkit = Toolkit.getDefaultToolkit();
currentImage = toolkit.getImage(fileName);
try
tracker.addImage(currentImage,11);
tracker.waitForID(11);
catch(InterruptedException e)
e.printStackTrace();
System.err.println("*ERROR* MediaTracker rudely interrupted.");
currentImage=null;
tracker.removeImage(currentImage);
pictureWidth = currentImage.getWidth(this);
pictureHeight = currentImage.getHeight(this);
handlepixels(currentImage, (getWidth() - pictureWidth)/2 - 60, 0,
pictureWidth, pictureHeight);
isFile = true;
repaint();
public void paintComponent(Graphics g)
if (currentImage != null && currentImage.getHeight(null)>=0)
super.paintComponent(g);
g.drawImage(currentImage, (this.getWidth() - 300)/2,
(this.getHeight() - 90)/2, this);
public byte[] sendPixel (byte byteArray[])
int numOfBits = 8, numOfBytesInLine = pictureWidth/8,
numOfLines = pictureHeight, countPixels = 0, gray,
currentPixel, bit = -1;
byte currentByte = 0;
int j = 0;
if (currentImage == null)
System.out.println("Picture has not been loaded yet");
return null;
else
for (int i = 0 ;i < pixels.length; i++)
currentPixel = manipulatePixel(pixels);
if (currentPixel > 128)
currentByte &= 0xfe;
else
currentByte |= 0x01;
bit++;
if (bit != 7)
currentByte <<= 1;
else
bit = -1;
byteArray[i/8] = currentByte;
currentByte = 0;
return byteArray;
public int manipulatePixel (int pixel)
return ((pixel&0xff)+((pixel&0xff00)>>8)+((pixel&0xff0000)>>16))/3;
public void handlepixels(Image img, int x, int y, int w, int h) {
System.out.println("w "+w+" h "+h);
pixels = new int[w * h];
int red, green, blue;
     PixelGrabber pg = new PixelGrabber (img, x, y, w, h, pixels, 0, w);
     try {
     if (pg.grabPixels()&&((pg.getStatus() & ImageObserver.ALLBITS) != 0))
else
System.out.println("Did not succeed to grab pixles");
catch (InterruptedException e) {
     System.err.println("interrupted waiting for pixels!");
     return;
repaint();
public int getNumOfLines () {return pictureHeight;}
public int getNumOfBytesInLine () {return pictureWidth/8;}
Thanks,
gabi

Answer 1

Method is somethig like this:
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)
          for (int j = 0; j < h; j++)
for (int i = 0; i < w; i++)
               //what do I need to do inside this loop?
     // Ineed to check pixel by pixel if it is certain color and then convert it to
               //different color.     
               Image new_image = Toolkit.getDefaultToolkit().createImage(new MemoryImageSource(w, h, image, 0, w));
     }