How can I get to read the pixels in an image?

Question

Please see details of my code below. What I am doing is trying to obtain the pixels for an image. there is an initial image of a certain size, which is then split into smaller portions.
The problem I'm getting is that pixels can not be read past the middle of the original image. I hope I have explained this so it can be understood. I have included the class that I am working on
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package MandelbrotConstruction.compression;
import java.awt.*;
import java.awt.color.ColorSpace;
import java.awt.geom.AffineTransform;
import java.awt.image.*;
import java.io.*;
import java.util.ArrayList;
import javax.imageio.ImageIO;
import javax.swing.JPanel;
* @author Charlene Hunter
public class DisplayImg extends JPanel {
    private static BufferedImage image;
    private static ArrayList<Range> rangeLot;
    private static ArrayList<Domain> domainLot;
    @Override
    public void paintComponent(Graphics g) {
        super.paintComponent(g);
        int w = MainFrame.getJPanel1().getWidth();
        int h = MainFrame.getJPanel1().getHeight();
        Graphics2D g2 = (Graphics2D) g;
        File img = MainFrame.getImgFile();
        image = null;
        if (img != null) {
            try {
                image = ImageIO.read(img);
                //filter the image with a grayscale
                ColorConvertOp grayOp = new ColorConvertOp(ColorSpace.getInstance(ColorSpace.CS_GRAY), null);
                image = grayOp.filter(image, null);
                //scale image to the size of the panel
                AffineTransform at = new AffineTransform();
                at.scale(256.0 / image.getWidth(), 256.0 / image.getHeight());
                AffineTransformOp resizeOp = new AffineTransformOp(at, null);
                image = resizeOp.filter(image, null);
                ArrayList<Range> r = createRanges(image, 3);
                ArrayList<Domain> d = createDomains(image);
                int i = 0;
                for (Domain dom : d) {
                    System.err.println("this is " + i);
                    System.out.println(dom.getPixels());
                    i++;
                CompareClass comparer = new CompareClass(r, d);
            } catch (IOException e) {
                System.err.println("IOException");
        g2.drawImage(image, null, 0, 0);
    public static ArrayList<Range> createRanges(BufferedImage bi, int divisions) {
        int w = bi.getWidth();
        int h = bi.getHeight();
        rangeLot = new ArrayList<Range>();
        int k = (int) Math.pow(2, divisions);
        for (int x = 0; x < w; x = x + (w / k)) {
            for (int y = 0; y < h; y = y + (h / k)) {
                BufferedImage range = bi.getSubimage(x, y, w / k, h / k);
                double[] pix = range.getRaster().getPixels(x, y, range.getWidth(), range.getHeight(), (double[]) null);
                Range r = new Range(x, y, range, pix);
                rangeLot.add(r);
        return rangeLot;
    public static ArrayList<Domain> createDomains(BufferedImage bi) {
        int w = bi.getWidth();
        int h = bi.getHeight();
        domainLot = new ArrayList<Domain>();
        int step = 4;
        for (int x = 0; x < w - step; x = x + step) {
            for (int y = 0; y < h - step; y = y + step) {
                BufferedImage domain = bi.getSubimage(x, y, 2 * step, 2 * step);
                double[] pix = domain.getRaster().getPixels(x, y, domain.getWidth(), domain.getHeight(), (double[]) null);
                Domain d = new Domain(x, y, domain, pix);
                domainLot.add(d);
        return domainLot;
}If what I have included is not sufficient, please let me know. the problem is only arising when the pixels are being obtained for the subimage
Thanks

Answer 1

Hi, the error message I am getting is (i'm printing out the x,y values and width and height so that I can see what going on) the whole image is 512x512, and I am grabbing pixels for squares of 64x64, but when it gets to 256 it throws an exception. I don'd understand why
(x: 0, y: 0)
width: 64, height: 64
done!
(x: 0, y: 64)
width: 64, height: 64
done!
(x: 0, y: 128)
width: 64, height: 64
done!
(x: 0, y: 192)
width: 64, height: 64
done!
(x: 0, y: 256)
width: 64, height: 64
Exception in thread "AWT-EventQueue-0" java.lang.ArrayIndexOutOfBoundsException: Coordinate out of bounds!
        at java.awt.image.ComponentSampleModel.getSampleDouble(ComponentSampleModel.java:807)
        at java.awt.image.SampleModel.getPixels(SampleModel.java:823)
        at java.awt.image.Raster.getPixels(Raster.java:1613)
        at MandelbrotConstruction.compression.DisplayImg.createRanges(DisplayImg.java:83)
        at MandelbrotConstruction.compression.DisplayImg.paintComponent(DisplayImg.java:51)
        at javax.swing.JComponent.paint(JComponent.java:1006)
        at javax.swing.JComponent.paintChildren(JComponent.java:843)
        at javax.swing.JComponent.paint(JComponent.java:1015)
        at javax.swing.JComponent.paintChildren(JComponent.java:843)
        at javax.swing.JComponent.paint(JComponent.java:1015)
        at javax.swing.JLayeredPane.paint(JLayeredPane.java:559)
        at javax.swing.JComponent.paintChildren(JComponent.java:843)
        at javax.swing.JComponent.paintWithOffscreenBuffer(JComponent.java:4979)
        at javax.swing.JComponent.paintDoubleBuffered(JComponent.java:4925)
        at javax.swing.JComponent.paint(JComponent.java:996)
        at java.awt.GraphicsCallback$PaintCallback.run(GraphicsCallback.java:21)
        at sun.awt.SunGraphicsCallback.runOneComponent(SunGraphicsCallback.java:60)
        at sun.awt.SunGraphicsCallback.runComponents(SunGraphicsCallback.java:97)
        at java.awt.Container.paint(Container.java:1709)
        at sun.awt.RepaintArea.paintComponent(RepaintArea.java:248)
        at sun.awt.RepaintArea.paint(RepaintArea.java:224)
        at sun.awt.windows.WComponentPeer.handleEvent(WComponentPeer.java:254)
        at java.awt.Component.dispatchEventImpl(Component.java:4060)
        at java.awt.Container.dispatchEventImpl(Container.java:2024)
        at java.awt.Window.dispatchEventImpl(Window.java:1791)
        at java.awt.Component.dispatchEvent(Component.java:3819)
        at java.awt.EventQueue.dispatchEvent(EventQueue.java:463)
        at java.awt.EventDispatchThread.pumpOneEventForHierarchy(EventDispatchThread.java:242)
        at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:163)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:157)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:149)
        at java.awt.EventDispatchThread.run(EventDispatchThread.java:110)