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/*=========================================================================
*
* Copyright Insight Software Consortium
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0.txt
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
*=========================================================================*/
//
// This example was originally contributed by Stephan in the users list
//
// http://public.kitware.com/pipermail/insight-users/2005-June/013482.html
//
//
// Software Guide : BeginLatex
//
// This example illustrates how to compute the direct Fourier transform
// followed by the inverse Fourier transform in order to recover the original
// data.
//
// Software Guide : EndLatex
#include "itkImage.h"
#include "itkImageFileReader.h"
#include "itkImageFileWriter.h"
#include "itkResampleImageFilter.h"
#include "itkVnlForwardFFTImageFilter.h"
#include "itkVnlInverseFFTImageFilter.h"
int main( int argc, char * argv[] )
{
if( argc != 3 )
{
std::cerr << "Usage: " << argv[0] << " input output" << std::endl;
return EXIT_FAILURE;
}
// Software Guide : BeginLatex
//
// First we set up the types of the input and output images.
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
const unsigned int Dimension = 2;
typedef unsigned short IOPixelType;
typedef float WorkPixelType;
typedef itk::Image< IOPixelType, Dimension > IOImageType;
typedef itk::Image< WorkPixelType, Dimension > WorkImageType;
// Software Guide : EndCodeSnippet
// File handling
typedef itk::ImageFileReader< IOImageType > ReaderType;
typedef itk::ImageFileWriter< IOImageType > WriterType;
ReaderType::Pointer inputreader = ReaderType::New();
WriterType::Pointer writer = WriterType::New();
inputreader->SetFileName( argv[1] );
writer->SetFileName( argv[2] );
// Handle padding of the image with resampling
typedef itk::ResampleImageFilter<
IOImageType,
WorkImageType > ResamplerType;
ResamplerType::Pointer inputresampler = ResamplerType::New();
inputresampler->SetDefaultPixelValue(0);
// Read the image and get its size
inputreader->Update();
IOImageType::SizeType inputsize;
IOImageType::SizeType worksize;
inputsize = inputreader->GetOutput()->GetLargestPossibleRegion().GetSize();
// worksize is the nearest multiple of 2 larger than the input
for( unsigned int i=0; i < 2; i++ )
{
unsigned int n=0;
worksize[i] = inputsize[i];
while( worksize[i] >>= 1 )
{
n++;
}
worksize[i] = static_cast<IOImageType::SizeValueType> ( 1 )
<< static_cast<IOImageType::SizeValueType>( n + 1 );
std::cout << "inputsize[" << i << "]=" << inputsize[i] << std::endl;
std::cout << "worksize[" << i << "]=" << worksize[i] << std::endl;
}
inputresampler->SetSize( worksize );
inputresampler->SetInput( inputreader->GetOutput() );
// Forward FFT filter
typedef itk::VnlForwardFFTImageFilter < WorkImageType > FFTFilterType;
FFTFilterType::Pointer fftinput = FFTFilterType::New();
fftinput->SetInput( inputresampler->GetOutput() );
// This is the output type from the FFT filters
typedef FFTFilterType::OutputImageType ComplexImageType;
// Do the inverse transform = forward transform / num voxels
typedef itk::VnlInverseFFTImageFilter < ComplexImageType > invFFTFilterType;
invFFTFilterType::Pointer fftoutput = invFFTFilterType::New();
fftoutput->SetInput(fftinput->GetOutput()); // try to recover the input image
// undo the padding
typedef itk::ResampleImageFilter<WorkImageType, IOImageType> ResampleOutType;
ResampleOutType::Pointer outputResampler = ResampleOutType::New();
outputResampler->SetDefaultPixelValue( 0 );
outputResampler->SetSize( inputsize );
outputResampler->SetInput( fftoutput->GetOutput() );
// Write the output
writer->SetInput(outputResampler->GetOutput());
writer->Update();
return EXIT_SUCCESS;
}
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