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/*=========================================================================
*
* Copyright NumFOCUS
*
* 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
*
* https://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.
*
*=========================================================================*/
#ifndef itkHalfHermitianToRealInverseFFTImageFilter_hxx
#define itkHalfHermitianToRealInverseFFTImageFilter_hxx
namespace itk
{
template <typename TInputImage, typename TOutputImage>
HalfHermitianToRealInverseFFTImageFilter<TInputImage, TOutputImage>::HalfHermitianToRealInverseFFTImageFilter()
{
this->ActualXDimensionIsOddOff();
}
template <typename TInputImage, typename TOutputImage>
void
HalfHermitianToRealInverseFFTImageFilter<TInputImage, TOutputImage>::GenerateOutputInformation()
{
// call the superclass' implementation of this method
Superclass::GenerateOutputInformation();
// get pointers to the input and output
typename InputImageType::ConstPointer inputPtr = this->GetInput();
typename OutputImageType::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. For an IFFT, since the
// spacing is propagated to the complex result, we can use the spacing
// from the input to propagate back to the output.
const typename InputImageType::SizeType & inputSize = inputPtr->GetLargestPossibleRegion().GetSize();
const typename InputImageType::IndexType & inputStartIndex = inputPtr->GetLargestPossibleRegion().GetIndex();
typename OutputImageType::SizeType outputSize;
typename OutputImageType::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.
// Going from complex to real, you know the output is at least
// twice the size in the last dimension as the input, but it might
// be 2*size+1. Consequently, you need to check whether the actual
// X dimension is even or odd.
outputSize[0] = (inputSize[0] - 1) * 2;
if (this->GetActualXDimensionIsOdd())
{
outputSize[0]++;
}
outputStartIndex[0] = inputStartIndex[0];
for (unsigned int i = 1; i < OutputImageType::ImageDimension; ++i)
{
outputSize[i] = inputSize[i];
outputStartIndex[i] = inputStartIndex[i];
}
const typename OutputImageType::RegionType outputLargestPossibleRegion(outputStartIndex, outputSize);
outputPtr->SetLargestPossibleRegion(outputLargestPossibleRegion);
}
template <typename TInputImage, typename TOutputImage>
void
HalfHermitianToRealInverseFFTImageFilter<TInputImage, TOutputImage>::GenerateInputRequestedRegion()
{
Superclass::GenerateInputRequestedRegion();
// Get pointers to the input and output
typename InputImageType::Pointer inputPtr = const_cast<InputImageType *>(this->GetInput());
if (inputPtr)
{
inputPtr->SetRequestedRegionToLargestPossibleRegion();
}
}
template <typename TInputImage, typename TOutputImage>
void
HalfHermitianToRealInverseFFTImageFilter<TInputImage, TOutputImage>::EnlargeOutputRequestedRegion(DataObject *)
{
this->GetOutput()->SetRequestedRegion(this->GetOutput()->GetLargestPossibleRegion());
}
template <typename TInputImage, typename TOutputImage>
SizeValueType
HalfHermitianToRealInverseFFTImageFilter<TInputImage, TOutputImage>::GetSizeGreatestPrimeFactor() const
{
return 2;
}
} // namespace itk
#endif
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