itkGradientDifferenceImageToImageMetric.h

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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
 *
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 *  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.
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 *=========================================================================*/
#ifndef itkGradientDifferenceImageToImageMetric_h
#define itkGradientDifferenceImageToImageMetric_h
 
#include "itkImageToImageMetric.h"
 
#include "itkSobelOperator.h"
#include "itkNeighborhoodOperatorImageFilter.h"
#include "itkPoint.h"
#include "itkCastImageFilter.h"
#include "itkResampleImageFilter.h"
 
namespace itk
{
template <typename TFixedImage, typename TMovingImage>
class ITK_TEMPLATE_EXPORT GradientDifferenceImageToImageMetric : public ImageToImageMetric<TFixedImage, TMovingImage>
{
public:
  ITK_DISALLOW_COPY_AND_MOVE(GradientDifferenceImageToImageMetric);

  using Self = GradientDifferenceImageToImageMetric;
  using Superclass = ImageToImageMetric<TFixedImage, TMovingImage>;
 
  using Pointer = SmartPointer<Self>;
  using ConstPointer = SmartPointer<const Self>;

  itkNewMacro(Self);

  itkOverrideGetNameOfClassMacro(GradientDifferenceImageToImageMetric);

  using typename Superclass::RealType;
  using typename Superclass::TransformType;
  using typename Superclass::TransformPointer;
  using typename Superclass::TransformParametersType;
  using typename Superclass::TransformJacobianType;
 
  using typename Superclass::MeasureType;
  using typename Superclass::DerivativeType;
  using typename Superclass::FixedImageType;
  using typename Superclass::MovingImageType;
  using typename Superclass::FixedImageConstPointer;
  using typename Superclass::MovingImageConstPointer;
 
  using FixedImagePixelType = typename TFixedImage::PixelType;
  using MovedImagePixelType = typename TMovingImage::PixelType;
 
  static constexpr unsigned int FixedImageDimension = TFixedImage::ImageDimension;
  using TransformedMovingImageType = itk::Image<FixedImagePixelType, Self::FixedImageDimension>;
 
  using TransformMovingImageFilterType = itk::ResampleImageFilter<MovingImageType, TransformedMovingImageType>;

 
  using FixedGradientImageType = itk::Image<RealType, Self::FixedImageDimension>;
 
  using CastFixedImageFilterType = itk::CastImageFilter<FixedImageType, FixedGradientImageType>;
  using CastFixedImageFilterPointer = typename CastFixedImageFilterType::Pointer;
 
  using FixedGradientPixelType = typename FixedGradientImageType::PixelType;

 
  static constexpr unsigned int MovedImageDimension = MovingImageType::ImageDimension;
 
  using MovedGradientImageType = itk::Image<RealType, Self::MovedImageDimension>;
 
  using CastMovedImageFilterType = itk::CastImageFilter<TransformedMovingImageType, MovedGradientImageType>;
  using CastMovedImageFilterPointer = typename CastMovedImageFilterType::Pointer;
 
  using MovedGradientPixelType = typename MovedGradientImageType::PixelType;

  void
  GetDerivative(const TransformParametersType & parameters, DerivativeType & derivative) const override;

  MeasureType
  GetValue(const TransformParametersType & parameters) const override;

  void
  GetValueAndDerivative(const TransformParametersType & parameters,
                        MeasureType &                   Value,
                        DerivativeType &                Derivative) const override;

  void
  Initialize() override;

  itkSetMacro(DerivativeDelta, double);
  itkGetConstReferenceMacro(DerivativeDelta, double);
 
protected:
  GradientDifferenceImageToImageMetric();
  ~GradientDifferenceImageToImageMetric() override = default;
  void
  PrintSelf(std::ostream & os, Indent indent) const override;

  void
  ComputeMovedGradientRange() const;

  void
  ComputeVariance() const;

  MeasureType
  ComputeMeasure(const TransformParametersType & parameters, const double * subtractionFactor) const;
 
  using FixedSobelFilter = NeighborhoodOperatorImageFilter<FixedGradientImageType, FixedGradientImageType>;
 
  using MovedSobelFilter = NeighborhoodOperatorImageFilter<MovedGradientImageType, MovedGradientImageType>;
 
private:
  mutable MovedGradientPixelType m_Variance[FixedImageDimension]{};

  mutable MovedGradientPixelType m_MinMovedGradient[MovedImageDimension]{};
  mutable MovedGradientPixelType m_MaxMovedGradient[MovedImageDimension]{};

  mutable FixedGradientPixelType m_MinFixedGradient[FixedImageDimension]{};
  mutable FixedGradientPixelType m_MaxFixedGradient[FixedImageDimension]{};

  typename TransformMovingImageFilterType::Pointer m_TransformMovingImageFilter{};

  CastFixedImageFilterPointer m_CastFixedImageFilter{};
 
  SobelOperator<FixedGradientPixelType, Self::FixedImageDimension> m_FixedSobelOperators[FixedImageDimension]{};
 
  typename FixedSobelFilter::Pointer m_FixedSobelFilters[Self::FixedImageDimension]{};
 
  ZeroFluxNeumannBoundaryCondition<MovedGradientImageType> m_MovedBoundCond{};
  ZeroFluxNeumannBoundaryCondition<FixedGradientImageType> m_FixedBoundCond{};

  CastMovedImageFilterPointer m_CastMovedImageFilter{};
 
  SobelOperator<MovedGradientPixelType, Self::MovedImageDimension> m_MovedSobelOperators[MovedImageDimension]{};
 
  typename MovedSobelFilter::Pointer m_MovedSobelFilters[Self::MovedImageDimension]{};
 
  double m_DerivativeDelta{};
};
} // end namespace itk
 
#ifndef ITK_MANUAL_INSTANTIATION
#  include "itkGradientDifferenceImageToImageMetric.hxx"
#endif
 
#endif