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ENH: Lambda functions instead of functor classes in JosephForwardProjectionFilter #694

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cbbaabb
ENH: Use lambda functions instead of functor classes in rtkJosephForw…
Feb 28, 2025
3b94ce7
ENH: Use lambda functions instead of functor classes in rtkJosephBack…
axel-grc Apr 22, 2026
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28 changes: 18 additions & 10 deletions applications/rtkprojectionmatrix/rtkprojectionmatrix.cxx
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Original file line number Diff line number Diff line change
Expand Up @@ -159,19 +159,28 @@ main(int argc, char * argv[])
if (args_info.verbose_flag)
std::cout << "Backprojecting volume and recording matrix values..." << std::endl;

auto backProjection = rtk::JosephBackProjectionImageFilter<
OutputImageType,
OutputImageType,
rtk::Functor::InterpolationWeightMultiplicationBackProjection<OutputPixelType, OutputPixelType>,
rtk::Functor::StoreSparseMatrixSplatWeightMultiplication<OutputPixelType, double, OutputPixelType>>::New();
auto backProjection = rtk::JosephBackProjectionImageFilter<OutputImageType, OutputImageType>::New();
backProjection->SetInput(constantImageSource->GetOutput());
backProjection->SetInput(1, reader->GetOutput());
backProjection->SetGeometry(geometry);
backProjection->GetSplatWeightMultiplication().SetProjectionsBuffer(reader->GetOutput()->GetBufferPointer());
backProjection->GetSplatWeightMultiplication().SetVolumeBuffer(constantImageSource->GetOutput()->GetBufferPointer());
backProjection->GetSplatWeightMultiplication().GetVnlSparseMatrix().resize(
// Create and configure a StoreSparseMatrixSplatWeightMultiplication instance
using SplatFunctorType =
rtk::Functor::StoreSparseMatrixSplatWeightMultiplication<OutputPixelType, double, OutputPixelType>;
auto splatFunctor = std::make_shared<SplatFunctorType>();
splatFunctor->SetProjectionsBuffer(reader->GetOutput()->GetBufferPointer());
splatFunctor->SetVolumeBuffer(constantImageSource->GetOutput()->GetBufferPointer());
splatFunctor->GetVnlSparseMatrix().resize(
reader->GetOutput()->GetLargestPossibleRegion().GetNumberOfPixels(),
constantImageSource->GetOutput()->GetLargestPossibleRegion().GetNumberOfPixels());

using WeightCoordinateType = typename itk::PixelTraits<OutputPixelType>::ValueType;
backProjection->SetSplatWeightMultiplication([splatFunctor](const OutputPixelType & rayValue,
OutputPixelType & output,
const double stepLengthInVoxel,
const double voxelSize,
const WeightCoordinateType weight) {
(*splatFunctor)(rayValue, output, stepLengthInVoxel, voxelSize, weight);
});
TRY_AND_EXIT_ON_ITK_EXCEPTION(backProjection->Update())

// Write matrix to disk
Expand All @@ -183,8 +192,7 @@ main(int argc, char * argv[])
std::cerr << "Failed to open " << args_info.output_arg << std::endl;
return EXIT_FAILURE;
}
rtk::MatlabSparseMatrix matlabSparseMatrix(backProjection->GetSplatWeightMultiplication().GetVnlSparseMatrix(),
backProjection->GetOutput());
rtk::MatlabSparseMatrix matlabSparseMatrix(splatFunctor->GetVnlSparseMatrix(), backProjection->GetOutput());
ofs << matlabSparseMatrix;
ofs.close();
return EXIT_SUCCESS;
Expand Down
182 changes: 9 additions & 173 deletions include/rtkJosephBackAttenuatedProjectionImageFilter.h
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Original file line number Diff line number Diff line change
Expand Up @@ -25,160 +25,7 @@

namespace rtk
{
namespace Functor
{
/** \class InterpolationWeightMultiplicationAttenuatedBackProjection
* \brief Function to multiply the interpolation weights with the projected
* volume values and attenuation map.
*
* \author Antoine Robert
*
* \ingroup RTK Functions
*/
template <class TInput, class TCoordinateType, class TOutput = TInput>
class ITK_TEMPLATE_EXPORT InterpolationWeightMultiplicationAttenuatedBackProjection
{
public:
InterpolationWeightMultiplicationAttenuatedBackProjection() { m_AttenuationPixel = 0; }

~InterpolationWeightMultiplicationAttenuatedBackProjection() = default;
bool
operator!=(const InterpolationWeightMultiplicationAttenuatedBackProjection &) const
{
return false;
}

bool
operator==(const InterpolationWeightMultiplicationAttenuatedBackProjection & other) const
{
return !(*this != other);
}

TOutput
operator()(const double stepLengthInVoxel, const TCoordinateType weight, const TInput * p, const int i)
{
const double w = weight * stepLengthInVoxel;

m_AttenuationPixel += w * (p + m_AttenuationMinusEmissionMapsPtrDiff)[i];
return w * (p + m_AttenuationMinusEmissionMapsPtrDiff)[i];
}

void
SetAttenuationMinusEmissionMapsPtrDiff(std::ptrdiff_t pd)
{
m_AttenuationMinusEmissionMapsPtrDiff = pd;
}
TOutput *
GetAttenuationPixel()
{
return &m_AttenuationPixel;
}

private:
std::ptrdiff_t m_AttenuationMinusEmissionMapsPtrDiff{};
TInput m_AttenuationPixel;
};

/** \class ComputeAttenuationCorrectionBackProjection
* \brief Function to compute the attenuation correction on the projection.
*
* \author Antoine Robert
*
* \ingroup RTK Functions
*/
template <class TInput, class TOutput>
class ITK_TEMPLATE_EXPORT ComputeAttenuationCorrectionBackProjection
{
public:
using VectorType = itk::Vector<double, 3>;

ComputeAttenuationCorrectionBackProjection() { m_Ex1 = 1; }

~ComputeAttenuationCorrectionBackProjection() = default;
bool
operator!=(const ComputeAttenuationCorrectionBackProjection &) const
{
return false;
}

bool
operator==(const ComputeAttenuationCorrectionBackProjection & other) const
{
return !(*this != other);
}

TOutput
operator()(const TInput rayValue, const TInput attenuationRay, const VectorType & stepInMM, bool & isNewRay)
{
if (isNewRay)
{
m_Ex1 = 1;
isNewRay = false;
}
TInput ex2 = exp(-attenuationRay * stepInMM.GetNorm());
TInput wf;
if (*m_AttenuationPixel > 0)
{
wf = (m_Ex1 - ex2) / *m_AttenuationPixel;
}
else
{
wf = m_Ex1 * stepInMM.GetNorm();
}

m_Ex1 = ex2;
*m_AttenuationPixel = 0;
return wf * rayValue;
}

void
SetAttenuationPixel(TInput * attenuationPixel)
{
m_AttenuationPixel = attenuationPixel;
}

private:
TInput m_Ex1;
TInput * m_AttenuationPixel;
};

/** \class SplatWeightMultiplicationAttenuated
* \brief Function to multiply the interpolation weights with the projection
* values.
*
* \author Cyril Mory
*
* \ingroup RTK Functions
*/
template <class TInput, class TCoordinateType, class TOutput = TCoordinateType>
class ITK_TEMPLATE_EXPORT SplatWeightMultiplicationAttenuated
{
public:
SplatWeightMultiplicationAttenuated() = default;
~SplatWeightMultiplicationAttenuated() = default;
bool
operator!=(const SplatWeightMultiplicationAttenuated &) const
{
return false;
}

bool
operator==(const SplatWeightMultiplicationAttenuated & other) const
{
return !(*this != other);
}

void
operator()(const TInput & rayValue,
TOutput & output,
const double stepLengthInVoxel,
const double itkNotUsed(voxelSize),
const TCoordinateType weight) const
{
output += rayValue * weight * stepLengthInVoxel;
}
};
} // end namespace Functor

/** \class JosephBackAttenuatedProjectionImageFilter
* \brief Attenuated Joseph back projection.
Expand All @@ -194,37 +41,21 @@ class ITK_TEMPLATE_EXPORT SplatWeightMultiplicationAttenuated
* \ingroup RTK Projector
*/

template <
class TInputImage,
class TOutputImage,
class TInterpolationWeightMultiplication = Functor::InterpolationWeightMultiplicationAttenuatedBackProjection<
typename TInputImage::PixelType,
typename itk::PixelTraits<typename TInputImage::PixelType>::ValueType>,
class TSplatWeightMultiplication = Functor::
SplatWeightMultiplicationAttenuated<typename TInputImage::PixelType, double, typename TOutputImage::PixelType>,
class TSumAlongRay = Functor::ComputeAttenuationCorrectionBackProjection<typename TInputImage::PixelType,
typename TOutputImage::PixelType>>
template <class TInputImage, class TOutputImage>
class ITK_TEMPLATE_EXPORT JosephBackAttenuatedProjectionImageFilter
: public JosephBackProjectionImageFilter<TInputImage,
TOutputImage,
TInterpolationWeightMultiplication,
TSplatWeightMultiplication,
TSumAlongRay>
: public JosephBackProjectionImageFilter<TInputImage, TOutputImage>
{
public:
ITK_DISALLOW_COPY_AND_MOVE(JosephBackAttenuatedProjectionImageFilter);

/** Standard class type alias. */
using Self = JosephBackAttenuatedProjectionImageFilter;
using Superclass = JosephBackProjectionImageFilter<TInputImage,
TOutputImage,
TInterpolationWeightMultiplication,
TSplatWeightMultiplication,
TSumAlongRay>;
using Superclass = JosephBackProjectionImageFilter<TInputImage, TOutputImage>;
using Pointer = itk::SmartPointer<Self>;
using ConstPointer = itk::SmartPointer<const Self>;
using InputPixelType = typename TInputImage::PixelType;
using OutputPixelType = typename TOutputImage::PixelType;
using WeightCoordinateType = typename itk::PixelTraits<InputPixelType>::ValueType;
using OutputImageRegionType = typename TOutputImage::RegionType;
using CoordinateType = double;
using VectorType = itk::Vector<CoordinateType, TInputImage::ImageDimension>;
Expand All @@ -244,6 +75,11 @@ class ITK_TEMPLATE_EXPORT JosephBackAttenuatedProjectionImageFilter
JosephBackAttenuatedProjectionImageFilter();
~JosephBackAttenuatedProjectionImageFilter() override = default;

std::ptrdiff_t m_AttenuationMinusEmissionMapsPtrDiff{ 0 };
InputPixelType m_AttenuationPixel{ static_cast<InputPixelType>(0) };
InputPixelType m_Ex1{ static_cast<InputPixelType>(1) };
const InputPixelType * m_AttenuationMapBuffer{ nullptr };

/** Apply changes to the input image requested region. */
void
GenerateInputRequestedRegion() override;
Expand Down
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