Help! Saving an image to stream and recreating it on client over network

Question

Hi,
I have an application that uses JDK 1.1.8. I am trying to capture the UI screens of this application over network to a client (another Java app running on a PC). The client uses JDK 1.3.0. As AWT image is not serializable, I got code that converts UI screens to int[] and persist to client socket as objectoutputstream.writeObject and read the data on client side using ObjectInputStream.readObject() api. Then I am converting the int[] to an Image. Then saving the image as JPEG file using JPEG encoder codec of JDK 1.3.0.
I found the image in black and white even though the UI screens are in color. I have the code below. I am sure JPEG encoder part is not doing that. I am missing something when recreating an image. Could be colormodel or the way I create an image on the client side. I am testing this code on a Win XP box with both server and client running on the same machine. In real scenario, the UI runs on an embedded system with pSOS with pretty limited flash space. I am giving below my code.
I appreciate any help or pointers.
Thanks
Puri
     public static String getImageDataHeader(Image img, String sImageName)
         final String HEADER = "{0} {1}x{2} {3}";
         String params[] = {sImageName,
                            String.valueOf(img.getWidth(null)),
                            String.valueOf(img.getHeight(null)),
                            System.getProperty("os.name")
         return MessageFormat.format(HEADER, params);
     public static int[] convertImageToIntArray(Image img)
         if (img == null)
             return null;
        int imgResult[] = null;
        try
            int nImgWidth = img.getWidth(null);
            int nImgHeight = img.getHeight(null);
            if (nImgWidth < 0 || nImgHeight < 0)
                Trace.traceError("Image is not ready");
                return null;
            Trace.traceInfo("Image size: " + nImgWidth + "x" + nImgHeight);
            imgResult = new int[nImgWidth*nImgHeight];
            PixelGrabber grabber = new PixelGrabber(img, 0, 0, nImgWidth, nImgHeight, imgResult, 0, nImgWidth);
            grabber.grabPixels();
            ColorModel model = grabber.getColorModel();
            if (null != model)
                Trace.traceInfo("Color model is " + model);
                int nRMask, nGMask, nBMask, nAMask;
                nRMask = model.getRed(0xFFFFFFFF);
                nGMask = model.getRed(0xFFFFFFFF);
                nBMask = model.getRed(0xFFFFFFFF);
                nAMask = model.getRed(0xFFFFFFFF);
                Trace.traceInfo("The Red mask: " + Integer.toHexString(nRMask) + ", Green mask: " +
                                Integer.toHexString(nGMask) + ", Blue mask: " +
                                Integer.toHexString(nBMask) + ", Alpha mask: " +
                                Integer.toHexString(nAMask));
            if ((grabber.getStatus() & ImageObserver.ABORT) != 0)
                Trace.traceError("Unable to grab pixels from the image");
                imgResult = null;
        catch(Throwable error)
            error.printStackTrace();
        return imgResult;
     public static Image convertIntArrayToImage(Component comp, int imgData[], int nWidth, int nHeight)
         if (imgData == null || imgData.length <= 0 || nWidth <= 0 || nHeight <= 0)
             return null;
        //ColorModel cm = new DirectColorModel(32, 0xFF0000, 0xFF00, 0xFF, 0xFF000000);
        ColorModel cm = ColorModel.getRGBdefault();
        MemoryImageSource imgSource = new MemoryImageSource(nWidth, nHeight, cm, imgData, 0, nWidth);
        //MemoryImageSource imgSource = new MemoryImageSource(nWidth, nHeight, imgData, 0, nWidth);
        Image imgDummy = Toolkit.getDefaultToolkit().createImage(imgSource);
        Image imgResult = comp.createImage(nWidth, nHeight);
        Graphics gc = imgResult.getGraphics();
        if (null != gc)
            gc.drawImage(imgDummy, 0, 0, nWidth, nHeight, null);       
            gc.dispose();
            gc = null;       
         return imgResult;
     public static boolean saveImageToStream(OutputStream out, Image img, String sImageName)
         boolean bResult = true;
         try
             ObjectOutputStream objOut = new ObjectOutputStream(out);
            int imageData[] = convertImageToIntArray(img);
            if (null != imageData)
                // Now that our image is ready, write it to server
                String sHeader = getImageDataHeader(img, sImageName);
                objOut.writeObject(sHeader);
                objOut.writeObject(imageData);
                imageData = null;
             else
                 bResult = false;
            objOut.flush();                
         catch(IOException error)
             error.printStackTrace();
             bResult = false;
         return bResult;
     public static Image readImageFromStream(InputStream in, Component comp, StringBuffer sbImageName)
         Image imgResult = null;
         try
             ObjectInputStream objIn = new ObjectInputStream(in);
             Object objData;
             objData = objIn.readObject();
             String sImageName, sSource;
             int nWidth, nHeight;
             if (objData instanceof String)
                 String sData = (String) objData;
                 int nIndex = sData.indexOf(' ');
                 sImageName = sData.substring(0, nIndex);
                 sData = sData.substring(nIndex+1);
                 nIndex = sData.indexOf('x');
                 nWidth = Math.atoi(sData.substring(0, nIndex));
                 sData = sData.substring(nIndex+1);
                 nIndex = sData.indexOf(' ');
                 nHeight = Math.atoi(sData.substring(0, nIndex));
                 sSource = sData.substring(nIndex+1);
                 Trace.traceInfo("Name: " + sImageName + ", Width: " + nWidth + ", Height: " + nHeight + ", Source: " + sSource);
                 objData = objIn.readObject();
                 if (objData instanceof int[])
                     int imgData[] = (int[]) objData;
                     imgResult = convertIntArrayToImage(comp, imgData, nWidth, nHeight);
                     sbImageName.setLength(0);
                     sbImageName.append(sImageName);
        catch(Exception error)
            error.printStackTrace();
         return imgResult;
     }   

Answer 1

While testing more, I found that the client side is generating color UI screens if I use JDK 1.3 JVM for running the server (i.e the side that generates the img) without changing single line of code. But if I use JDK 1.1.8 JVM for the server, the client side is generating black and white versions (aka gray toned) of UI screens. So I added code to save int array that I got from PixelGrabber to a text file with 8 ints for each line in hex format. Generated these files on server side with JVM 1.1.8 and JVM 1.3. What I found is that the 1.1.8 pixel grabber is setting R,G,B components to same value where as 1.3 version is setting them to different values thus resulting in colored UI screens. I don't know why.