[vtkusers] Please I need help on vtkImageFFT and vtkImageRFFT

[Stefan Huber]

Hi at all

I have one major problem with the vtkImageFFT and vtkImageRFFT.
I should make a mehode which uses vtkImageFFT to shift the image to the frequency space. After thr transformation, i should display the transformed image in an special software (nothing with vtk). Another mehtode should be generated, which takes the transformed picture and uses the vtkImageRFFT. This picture should also be displayed in the software.

When i o the FFT and display the image, i dont get a correct pictrue in the freuquency space. But when i do the RFFT on this picture i get the original image back. 
So I tried to generate the correct image after the FFT, but now nothing is correct. (FFT and RFFT)

Do you have an idea how i can do it right? This is my code of the FFT:

vtkImageFFT *ffft = vtkImageFFT::New();
ffft->SetDimensionality(2);
ffft->SetInput(img);
ffft->Update();

vtkImageFourierCenter *center = vtkImageFourierCenter::New();
vtkImageMagnitude *mag= vtkImageMagnitude::New();
vtkImageLogarithmicScale *log= vtkImageLogarithmicScale ::New();

mag->SetInputConnection(ffft->GetOutputPort());
mag->ReleaseDataFlagOff();

center->SetInputConnection(mag->GetOutputPort());
center->Update();

log->SetInputConnection(center->GetOutputPort());
log->SetConstant(5);
log->Update();

//now fill outputarray
for (i = 0; i< lenImg; i++){
  out[i] = log->GetOutput()->GetPointData()->GetComponent(id,0);
  id ++;
}


And thats my source for the RFFT:

vtkImageRFFT * rfft ) vtkImageRFFT::New();
rfft->SetDimensionality(2);
rfft->SetInput(img);
rfft->Update();
//prepare output
for (i = 0; i< sizeImg; i++){
  im = rfft->GetOutput()->GetPointData()->GetScalars()->getComponent(id,1);
  re = rfft->GetOutput()->GetPointData()->GetScalars()->getComponent(id,0);
  out[idx] = re;
  idx++; 
  out[idx] = im;
  id++;
  idx++;
}

please help me thanks
Stefan
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