Converting awt to JAI image - please help!

Question

My application needs to be able to create a JAI image and apply dither to it.
I got this working by using the fileload operator in JAI to load the image and convert it to a planar image but when I try to use the awtImage operator to convert the images to planar images it doesn't work.
I really don't understand why this is. The two methods are pratically identical.
This is the method that works and the error diffusion method
public void setDitherOp(String op, String picName,KernelJAI typeDither)
                      //operation name, parameter block
    srcImg = JAI.create("fileload", "Pics/"+picName);
    dataType = srcImg.getSampleModel().getDataType();
              //contains parameters to be used in dither operation
    pb = new ParameterBlock();
    pb.addSource(srcImg);
    layout = new ImageLayout();
    if(op=="ordered")
      orderedDither();
    else if(op=="error")
      errorDiffDither(typeDither);
public void errorDiffDither(KernelJAI typeDither)
      if(srcImg.getNumBands()==1)   //source image has one color band
        LookupTableJAI lut =new LookupTableJAI(new byte[] {(byte)0x00, (byte)0xff});
        pb.add(lut);
        pb.add(typeDither);
        byte[] map = new byte[] {(byte)0x00, (byte)0xff};
        ColorModel cm = new IndexColorModel(1, 2, map, map, map);
        layout.setColorModel(cm);
      else if(srcImg.getNumBands()==3)  //source image has three color bands
        pb.add(ColorCube.BYTE_496);  //add color cube to parameter block
        pb.add(typeDither);          //add error filter kernel
        System.out.println("error diffusion num bands is: "+srcImg.getNumBands());
      RenderingHints rhints = new RenderingHints(JAI.KEY_IMAGE_LAYOUT, layout);
      ditheredImage = JAI.create("errordiffusion", pb, rhints);
      if(ditheredImage==null)System.out.println("Dithered image is NULL");
This is the one that doesn't!
public void setDitherOp(String op, Image frameImage,KernelJAI typeDither)
    srcImg = JAI.create("AWTImage", frameImage);
    dataType = srcImg.getSampleModel().getDataType();
              //contains parameters to be used in dither operation
    pb = new ParameterBlock();
    pb.addSource(srcImg);
    if(srcImg==null)System.out.println("src image null in set dither op");
    /*if(srcImg!=null)
        ditheredImage = JAI.create("Invert", pb);
    layout = new ImageLayout();
    if(op=="ordered")
      orderedDither();
    else if(op=="error")
      errorDiffDither(typeDither);
public PlanarImage getDitheredImage()
    return ditheredImage;
  }The other really odd thing in the method that uses the awtImage operator is this:
if the code to invert the colours is executed it works fine. This must mean that it is creating the planar image from the awt image? I really don't see what the problem could be in that case because it uses the same error diffusion method after that.
Please help me with this - its part of a project thats due up in a few days and I really need to get this part working as soon as possible.
CurtinR

Answer 1

Hi morgair,
Thank you so much for answering!!
You're right - the FileLoad and awtImage operators return different types of objects.
FileLoad returns a RenderedImage
JAI.create("fileload", "Pics/"+picName);awtImage returns a PlanarImage. The sample model and color model are set according to the AWT image data.
srcImg = (PlanarImage)JAI.create("AWTImage", pbAwtOp);Also the error diffusion operation takes a renderedImage as a parameter. It says in the programming guide that the source image and the color map must have the same data type and number of bands. (That would explain why the method using fileLoad worked!)
How do I change the Planar image to a rendered imaage or specify the sample model and colour model of srcImg. I've been trying to do this but am going round in circles - there are descrepancies between the programmers guide and the API and I'm lost..
Any suggestions really really appreciated..