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itkFFTRealToComplexConjugateImageFilter.txx
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itkFFTRealToComplexConjugateImageFilter.txx
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/*=========================================================================
Program: Insight Segmentation & Registration Toolkit
Module: itkFFTRealToComplexConjugateImageFilter.txx
Language: C++
Date: $Date$
Version: $Revision$
Copyright (c) 2002 Insight Consortium. All rights reserved.
See ITKCopyright.txt or http://www.itk.org/HTML/Copyright.htm for details.
This software is distributed WITHOUT ANY WARRANTY; without even
the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
PURPOSE. See the above copyright notices for more information.
=========================================================================*/
#ifndef __itkFFTRealToComplexConjugateImageFilter_txx
#define __itkFFTRealToComplexConjugateImageFilter_txx
#include "itkFFTRealToComplexConjugateImageFilter.h"
#include "itkMetaDataObject.h"
namespace itk
{
template < class TPixel , unsigned int Dimension >
void
FFTRealToComplexConjugateImageFilter < TPixel , Dimension >
::GenerateOutputInformation()
{
// call the superclass' implementation of this method
Superclass::GenerateOutputInformation();
//
// If this implementation returns a full result
// instead of a 'half-complex' matrix, then none of this
// is necessary
if(this->FullMatrix())
return;
// get pointers to the input and output
typename TInputImageType::ConstPointer inputPtr = this->GetInput();
typename TOutputImageType::Pointer outputPtr = this->GetOutput();
if ( !inputPtr || !outputPtr )
{
return;
}
//
// This is all based on the same function in itk::ShrinkImageFilter
// ShrinkImageFilter also modifies the image spacing, but spacing
// has no meaning in the result of an FFT.
unsigned int i;
const typename TInputImageType::SizeType& inputSize
= inputPtr->GetLargestPossibleRegion().GetSize();
const typename TInputImageType::IndexType& inputStartIndex
= inputPtr->GetLargestPossibleRegion().GetIndex();
typename TOutputImageType::SizeType outputSize;
typename TOutputImageType::IndexType outputStartIndex;
//
// in 4.3.4 of the FFTW documentation, they indicate the size of
// of a real-to-complex FFT is N * N ... + (N /2+1)
// 1 2 d
// complex numbers.
// static_cast prob. not necessary but want to make sure integer
// division is used.
outputSize[0] = static_cast<unsigned int>(inputSize[0])/2 + 1;
outputStartIndex[0] = inputStartIndex[0];
for (i = 1; i < TOutputImageType::ImageDimension; i++)
{
outputSize[i] = inputSize[i];
outputStartIndex[i] = inputStartIndex[i];
}
//
// the halving of the input size hides the actual size of the input.
// to get the same size image out of the IFFT, need to send it as
// Metadata.
typedef typename TOutputImageType::SizeType::SizeValueType SizeScalarType;
itk::MetaDataDictionary &OutputDic=outputPtr->GetMetaDataDictionary();
itk::EncapsulateMetaData<SizeScalarType>(OutputDic,
std::string("FFT_Actual_RealImage_Size"),
inputSize[0]);
typename TOutputImageType::RegionType outputLargestPossibleRegion;
outputLargestPossibleRegion.SetSize( outputSize );
outputLargestPossibleRegion.SetIndex( outputStartIndex );
outputPtr->SetLargestPossibleRegion( outputLargestPossibleRegion );
}
}
#endif