ImageFFT

VTKExamples/Java/Images/ImageFFT


Description

vtkImageFFT object implements a fast Fourier transform.

The input can have real or complex data in any components and data types, but the output is always complex doubles with real values in component0, and imaginary values in component1.

The filter is fastest for images that have power of two sizes. The filter uses a butterfly diagram for each prime factor of the dimension.

This makes images with prime number dimensions (i.e. 17x17) much slower to compute. Multi dimensional (i.e volumes) FFT's are decomposed so that each axis executes serially.

Other Languages

See (Cxx)

Question

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Code

ImageFFT.java

import vtk.vtkNativeLibrary;
import vtk.vtkRenderWindow;
import vtk.vtkRenderWindowInteractor;
import vtk.vtkRenderer;
import vtk.vtkNamedColors;
import vtk.vtkImageEllipsoidSource;
import vtk.vtkImageFFT;
import vtk.vtkImageCast;
import vtk.vtkImageActor;
import vtk.vtkInteractorStyleImage;

public class ImageFFT
{
  // -----------------------------------------------------------------
  // Load VTK library and print which library was not properly loaded
  static 
  {
    if (!vtkNativeLibrary.LoadAllNativeLibraries()) 
    {
      for (vtkNativeLibrary lib : vtkNativeLibrary.values()) 
      {
        if (!lib.IsLoaded()) 
        {
          System.out.println(lib.GetLibraryName() + " not loaded");
        }
      }
    }
    vtkNativeLibrary.DisableOutputWindow(null);
  }
  // -----------------------------------------------------------------

  public static void main(String args[]) 
  {
    vtkNamedColors Color = new vtkNamedColors(); 

    double OriginalRendererBgColor[] = new double[] {.4, .5, .6, 1};
    Color.SetColor("OriginalRendererBgColor",OriginalRendererBgColor);

    double fftRendererBgColor[] = new double[] {.4, .5, .7, 1};
    Color.SetColor("fftRendererBgColor",fftRendererBgColor);

    //Create an image
    vtkImageEllipsoidSource source = new vtkImageEllipsoidSource();
    source.SetWholeExtent(0, 20, 0, 20, 0, 0);
    source.SetCenter(10,10,0);
    source.SetRadius(3,4,0);
    source.Update();

    vtkImageFFT fftFilter = new vtkImageFFT();
    fftFilter.SetInputConnection(source.GetOutputPort());
    fftFilter.Update();

    vtkImageCast fftCastFilter = new vtkImageCast();
    fftCastFilter.SetInputConnection(fftFilter.GetOutputPort());
    fftCastFilter.SetOutputScalarTypeToUnsignedChar();
    fftCastFilter.Update();

    //Create actors
    vtkImageActor originalActor = new vtkImageActor();
    originalActor.GetMapper().SetInputConnection(source.GetOutputPort());

    vtkImageActor fftActor = new vtkImageActor();
    fftActor.GetMapper().SetInputConnection(fftCastFilter.GetOutputPort());

    //Define viewport ranges
    //(xmin, ymin, xmax, ymax)
    double originalViewport[]= new double[] {0.0, 0.0, 0.5, 1.0};
    double fftViewport[] = new double[] {0.5, 0.0, 1.0, 1.0};

    //Setup renderers
    vtkRenderer originalRenderer = new vtkRenderer();
    originalRenderer.SetViewport(originalViewport);
    originalRenderer.AddActor(originalActor);
    originalRenderer.ResetCamera();
    originalRenderer.SetBackground(OriginalRendererBgColor);

    vtkRenderer fftRenderer = new vtkRenderer();
    fftRenderer.SetViewport(fftViewport);
    fftRenderer.AddActor(fftActor);
    fftRenderer.ResetCamera();
    fftRenderer.SetBackground(fftRendererBgColor);

    vtkRenderWindow renderWindow = new vtkRenderWindow();
    renderWindow.SetSize(600, 300);
    renderWindow.AddRenderer(originalRenderer);
    renderWindow.AddRenderer(fftRenderer);

    vtkRenderWindowInteractor renderWindowInteractor = new vtkRenderWindowInteractor();
    vtkInteractorStyleImage style = new vtkInteractorStyleImage();

    renderWindowInteractor.SetInteractorStyle(style);

    renderWindowInteractor.SetRenderWindow(renderWindow);
    renderWindow.Render();
    renderWindowInteractor.Initialize();

    renderWindowInteractor.Start();

  }
}