rtkReconstructionConjugateGradientOperator.h

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 *  Copyright RTK Consortium
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 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
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 *  distributed under the License is distributed on an "AS IS" BASIS,
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 *  See the License for the specific language governing permissions and
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#ifndef rtkReconstructionConjugateGradientOperator_h
#define rtkReconstructionConjugateGradientOperator_h

#include <itkMultiplyImageFilter.h>
#include <itkAddImageFilter.h>

#include "rtkConstantImageSource.h"

#include "rtkConjugateGradientOperator.h"
#include "rtkBackProjectionImageFilter.h"
#include "rtkForwardProjectionImageFilter.h"

#include "rtkThreeDCircularProjectionGeometry.h"
#include "rtkLaplacianImageFilter.h"
#include "rtkBlockDiagonalMatrixVectorMultiplyImageFilter.h"

#ifdef RTK_USE_CUDA
#  include "rtkCudaConstantVolumeSource.h"
#  include "rtkCudaLaplacianImageFilter.h"
#endif

namespace rtk
{

template <typename TOutputImage, typename TSingleComponentImage = TOutputImage, typename TWeightsImage = TOutputImage>
class ITK_TEMPLATE_EXPORT ReconstructionConjugateGradientOperator : public ConjugateGradientOperator<TOutputImage>
{
public:
  ITK_DISALLOW_COPY_AND_MOVE(ReconstructionConjugateGradientOperator);

  using Self = ReconstructionConjugateGradientOperator;
  using Superclass = ConjugateGradientOperator<TOutputImage>;
  using Pointer = itk::SmartPointer<Self>;
  using VectorPixelType = itk::CovariantVector<typename TOutputImage::ValueType, TOutputImage::ImageDimension>;
  using GradientImageType =
    typename TOutputImage::template RebindImageType<VectorPixelType, TOutputImage::ImageDimension>;

  itkNewMacro(Self);

  void
  SetInputVolume(const TOutputImage * vol);
  void
  SetInputProjectionStack(const TOutputImage * projs);
  void
  SetInputWeights(const TWeightsImage * weights);

  itkOverrideGetNameOfClassMacro(ReconstructionConjugateGradientOperator);

  using BackProjectionFilterType = rtk::BackProjectionImageFilter<TOutputImage, TOutputImage>;
  using BackProjectionFilterPointer = typename BackProjectionFilterType::Pointer;

  using ForwardProjectionFilterType = rtk::ForwardProjectionImageFilter<TOutputImage, TOutputImage>;
  using ForwardProjectionFilterPointer = typename ForwardProjectionFilterType::Pointer;

  using ConstantSourceType = rtk::ConstantImageSource<TOutputImage>;
  using MultiplyFilterType = itk::MultiplyImageFilter<TOutputImage, TSingleComponentImage>;
  using AddFilterType = itk::AddImageFilter<TOutputImage>;

  // If TOutputImage is an itk::Image of floats or double, so are the weights, and a simple Multiply filter is required
  // If TOutputImage is an itk::Image of itk::Vector<float (or double)>, a BlockDiagonalMatrixVectorMultiply filter
  // is needed. Thus the meta-programming construct
  using MatrixVectorMultiplyFilterType = rtk::BlockDiagonalMatrixVectorMultiplyImageFilter<TOutputImage, TWeightsImage>;
  using PlainMultiplyFilterType = itk::MultiplyImageFilter<TOutputImage, TOutputImage, TOutputImage>;
  using MultiplyWithWeightsFilterType = typename std::conditional_t<std::is_same_v<TSingleComponentImage, TOutputImage>,
                                                                    PlainMultiplyFilterType,
                                                                    MatrixVectorMultiplyFilterType>;

  using OutputImagePointer = typename TOutputImage::Pointer;

  void
  SetBackProjectionFilter(BackProjectionFilterType * _arg);

  void
  SetForwardProjectionFilter(ForwardProjectionFilterType * _arg);

  void
  SetSupportMask(const TSingleComponentImage * SupportMask);
  typename TSingleComponentImage::ConstPointer
  GetSupportMask();

  void
  SetLocalRegularizationWeights(const TSingleComponentImage * localRegularizationWeights);
  typename TSingleComponentImage::ConstPointer
  GetLocalRegularizationWeights();

  itkSetConstObjectMacro(Geometry, ThreeDCircularProjectionGeometry);

  itkSetMacro(Gamma, float);
  itkGetMacro(Gamma, float);
  itkSetMacro(Tikhonov, float);
  itkGetMacro(Tikhonov, float);

protected:
  ReconstructionConjugateGradientOperator();
  ~ReconstructionConjugateGradientOperator() override = default;

  void
  VerifyPreconditions() const override;

  void
  GenerateData() override;

  template <typename ImageType>
  typename std::enable_if<std::is_same_v<TSingleComponentImage, ImageType>, ImageType>::type::Pointer
  ConnectGradientRegularization();

  template <typename ImageType>
  typename std::enable_if<!std::is_same_v<TSingleComponentImage, ImageType>, ImageType>::type::Pointer
  ConnectGradientRegularization();

  BackProjectionFilterPointer    m_BackProjectionFilter;
  ForwardProjectionFilterPointer m_ForwardProjectionFilter;

  typename ConstantSourceType::Pointer                                  m_ConstantProjectionsSource;
  typename ConstantSourceType::Pointer                                  m_ConstantVolumeSource;
  typename MultiplyFilterType::Pointer                                  m_MultiplyOutputVolumeFilter;
  typename MultiplyFilterType::Pointer                                  m_MultiplyInputVolumeFilter;
  typename MultiplyFilterType::Pointer                                  m_MultiplyLaplacianFilter;
  typename MultiplyFilterType::Pointer                                  m_MultiplyTikhonovFilter;
  typename MultiplyFilterType::Pointer                                  m_MultiplyTikhonovWeightsFilter;
  typename AddFilterType::Pointer                                       m_AddLaplacianFilter;
  typename AddFilterType::Pointer                                       m_AddTikhonovFilter;
  typename itk::ImageToImageFilter<TOutputImage, TOutputImage>::Pointer m_LaplacianFilter;
  typename MultiplyWithWeightsFilterType::Pointer                       m_MultiplyWithWeightsFilter;

  rtk::ThreeDCircularProjectionGeometry::ConstPointer m_Geometry{ nullptr };
  float                                               m_Gamma{ 0 };    // Strength of the laplacian regularization
  float                                               m_Tikhonov{ 0 }; // Strength of the Tikhonov regularization

  typename TOutputImage::Pointer m_FloatingInputPointer, m_FloatingOutputPointer;

  void
  VerifyInputInformation() const override
  {}

  void
  GenerateInputRequestedRegion() override;
  void
  GenerateOutputInformation() override;

  typename TOutputImage::ConstPointer
  GetInputVolume();
  typename TOutputImage::ConstPointer
  GetInputProjectionStack();
  typename TWeightsImage::ConstPointer
  GetInputWeights();
};
} // namespace rtk


#ifndef ITK_MANUAL_INSTANTIATION
#  include "rtkReconstructionConjugateGradientOperator.hxx"
#endif

#endif