IOImage.write showing error after byte[] to BufferedImage

Question

I am new to Image Manipulations in Java and I am writing some program related to Image Steganography by Mapping Pixels to Letters..
I have successfully read the data from gray scale image to BufferedImage object and read the pixels in byte array..
byte []data;
DataBufferByte buffer = (DataBufferByte) image.getRaster().getDataBuffer();
data = buffer.getData();Now for testing the working of my pixel morphing I have changed two pixels data[0] and data[1] and tried to store it in some target.jpg file.. For that I used
image.data[0]=(byte)3;
image.data[1]=(byte)1;
InputStream in = new ByteArrayInputStream(image.data);
    try {
            BufferedImage img = javax.imageio.ImageIO.read(in);
            image.write(img, ref);
        } catch (IOException ex) {
            Logger.getLogger(Main.class.getName()).log(Level.SEVERE, null, ex);
Now I am getting error because ImageIO.read is returning NULL to BufferedImage img.. hence write method is throwing IllegalArgumentException.
I am totally lost.. please help me..
Edited by: Neo_Cerf on Feb 22, 2010 8:01 PM

Answer 1

Wrap the byte array in a DataBufferByte. Create an appropriate raster via one of the Raster#createXXXRaster methods. Then create and appropriate ColorModel and use the BufferedImage constructor that takes a raster and a color model. For a byte[] array representing gray data, this would be done like so.
byte[] imgData = ...;
int w = ...;
int h = ...;
//the DataBuffer
DataBuffer db = new DataBufferByte(imgData,imgData.length);
//the Raster
WritableRaster rast =  Raster.createInterleavedRaster(
       db, w, h, w, 1, new int[]{0}, null);
//the ColorModel
ColorSpace cs = ColorSpace.getInstance(ColorSpace.CS_GRAY);
ColorModel cm = new ComponentColorModel(
       cs,new int[]{8}, false, true,
       java.awt.Transparency.OPAQUE,
       DataBuffer.TYPE_BYTE);
//the BufferedImage
BufferedImage img = new BufferedImage(cm,rast,true,null);