DFT problem in JAI

Question

Hello!
I have a strange problem with the JAI classes that perform DFT and IDFT. I perform both the operations on an image but the result I get is not the original image. What 's wrong with my code?
Thanks for the help.
My code is as follows
import javax.media.jai.*;
import javax.media.jai.operator.*;
import java.awt.image.renderable.*;
import java.awt.image.*;
import java.awt.*;
import java.awt.event.*;
import java.awt.color.*;
import javax.swing.*;
import com.sun.image.codec.jpeg.*;
import java.awt.RenderingHints;
public class dftchain extends JPanel{
     PlanarImage img1;
     PlanarImage img2;
     PlanarImage finim;
     BufferedImage im;
     ImagePanel viewer;
     public static void main(String[] args) {
          dftchain s = new dftchain();
     public dftchain() {
     Image im1= readImage("ref.jpg");
     img1 = JAI.create("awtimage", im1);
     PlanarImage gray1 = convertColorToGray(img1,30);
     RenderedOp rop1 = DFTImage(gray1, DFTDescriptor.SCALING_NONE, DFTDescriptor.REAL_TO_COMPLEX);
     RenderedOp mag = magnitudeImage(rop1);
     RenderedOp refphase = phaseImage(rop1);
     RenderedOp complex = polarToComplexImage(mag, refphase);
     PlanarImage finim = inverseDFTImage(complex,DFTDescriptor.SCALING_NONE, DFTDescriptor.COMPLEX_TO_REAL);
     im = finim.getAsBufferedImage();
     diplay(im);
     public RenderedOp DFTImage (PlanarImage image, DFTScalingType scalingType, DFTDataNature dataNature){
          ParameterBlock pb = new ParameterBlock();
          pb.addSource(image);
          pb.add(scalingType).add(dataNature);
          return JAI.create("dft",pb);
     public RenderedOp inverseDFTImage (PlanarImage image, DFTScalingType scalingType, DFTDataNature dataNature) {
          ParameterBlock pb = new ParameterBlock();
          pb.addSource(image);
          pb.add(scalingType).add(dataNature);
          return JAI.create("idft", pb);
     public RenderedOp magnitudeImage (PlanarImage image){
          ParameterBlock pb = new ParameterBlock();
          pb.addSource(image);
          return JAI.create("magnitude",pb);
     public RenderedOp phaseImage (PlanarImage image){
          ParameterBlock pb = new ParameterBlock();
          pb.addSource(image);
          return JAI.create("phase",pb);
     public RenderedOp polarToComplexImage( RenderedOp mag, RenderedOp phase) {
          ParameterBlock pb = new ParameterBlock();
          pb.addSource(mag);
          pb.addSource(phase);
          return JAI.create("polartocomplex", pb);
     public void diplay (BufferedImage img) {
          int width = img.getWidth();
          int height = img.getHeight();
          JFrame fr = new JFrame();
          fr.addWindowListener(
          new WindowAdapter() {
               public void windowClosing(WindowEvent e){
                    System.exit(0);
          fr.setTitle("Viewer");
          viewer = new ImagePanel(img);
          viewer.setPreferredSize(new Dimension(width,height));
          Container cp = fr.getContentPane();
          fr.getContentPane().setLayout(new GridLayout(1,1));
          cp.add(viewer);
          fr.pack();
          fr.getSize(new Dimension(width, height));
          fr.show();
          viewer.repaint();
     public Image readImage(String imageName) {
          Image image = Toolkit.getDefaultToolkit().getImage(imageName);
          MediaTracker imageTracker = new MediaTracker(this);
          imageTracker.addImage(image,0);
          try{
               imageTracker.waitForID(0);
          catch (InterruptedException e) {
               System.out.println(e);
          return image;
     // produce a 3 band luminance image from a 3 band color image */
    public PlanarImage convertColorToGray(PlanarImage src, int brightness) {
        PlanarImage dst = null;
        double b = (double) brightness;
        double[][] matrix = {
                                { .114D, 0.587D, 0.299D, b },
                                { .114D, 0.587D, 0.299D, b },
                                { .114D, 0.587D, 0.299D, b }
        if ( src != null ) {
            ParameterBlock pb = new ParameterBlock();
            pb.addSource(src);
            pb.add(matrix);
            dst = JAI.create("bandcombine", pb, null);
        return dst;
    class ImagePanel extends JComponent {
          BufferedImage image;
          public ImagePanel (BufferedImage img) {
               image = img;
          public void paintComponent(Graphics g) {
               Rectangle rect = this.getBounds();
               if (image!=null){
                    g.drawImage(image,0,0,rect.width,rect.height,this);
}

Answer 1

I am not saying it will work, but I would ask if you tried "Dilate"? I don't know what the parameters are supposed to be for the different methods, but I do know how to get a listing of them. See the code below:
          OperationRegistry ory = JAI.getDefaultInstance().getOperationRegistry();
          String [] temp = ory.getRegistryModes();
          String []temp2;
          for (int which = 0; which < temp.length; which++) {
               temp2 = ory.getDescriptorNames(temp[which]);
               System.out.println("\t"+temp[which]+":");
               for (int cual = 0; cual < temp2.length; cual++) {
                    System.out.println("\t\t"+temp2[cual]);
That will get you a listing of all of the registry modes and the descriptor names within each mode. For parameters and explanations, well, I guess check out the source code for the JAI library and then rifle through it until you find an example, or use trial-and-error, since the only documentation seems to refer to deprecated calls (as I have noted in the most recent version of JAI).