itkMattesMutualInformationImageToImageMetricv4.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
 *
 *  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 itkMattesMutualInformationImageToImageMetricv4_h
#define itkMattesMutualInformationImageToImageMetricv4_h
 
#include "itkImageToImageMetricv4.h"
#include "itkMattesMutualInformationImageToImageMetricv4GetValueAndDerivativeThreader.h"
#include "itkPoint.h"
#include "itkIndex.h"
#include "itkBSplineDerivativeKernelFunction.h"
#include "itkArray2D.h"
#include "itkThreadedIndexedContainerPartitioner.h"
#include <mutex>
 
namespace itk
{

template <typename TFixedImage,
          typename TMovingImage,
          typename TVirtualImage = TFixedImage,
          typename TInternalComputationValueType = double,
          typename TMetricTraits =
            DefaultImageToImageMetricTraitsv4<TFixedImage, TMovingImage, TVirtualImage, TInternalComputationValueType>>
class ITK_TEMPLATE_EXPORT MattesMutualInformationImageToImageMetricv4
  : public ImageToImageMetricv4<TFixedImage, TMovingImage, TVirtualImage, TInternalComputationValueType, TMetricTraits>
{
public:
  ITK_DISALLOW_COPY_AND_MOVE(MattesMutualInformationImageToImageMetricv4);

  using Self = MattesMutualInformationImageToImageMetricv4;
  using Superclass =
    ImageToImageMetricv4<TFixedImage, TMovingImage, TVirtualImage, TInternalComputationValueType, TMetricTraits>;
  using Pointer = SmartPointer<Self>;
  using ConstPointer = SmartPointer<const Self>;

  itkNewMacro(Self);

  itkOverrideGetNameOfClassMacro(MattesMutualInformationImageToImageMetricv4);

  using typename Superclass::MeasureType;
  using typename Superclass::DerivativeType;
  using DerivativeValueType = typename DerivativeType::ValueType;
 
  using typename Superclass::FixedImageType;
  using typename Superclass::FixedImagePointType;
  using typename Superclass::FixedImageIndexType;
  using typename Superclass::FixedImagePixelType;
  using typename Superclass::FixedImageGradientType;
 
  using typename Superclass::MovingImagePointType;
  using typename Superclass::MovingImagePixelType;
  using typename Superclass::MovingImageGradientType;
 
  using typename Superclass::MovingTransformType;
  using typename Superclass::JacobianType;
  using VirtualImageType = typename Superclass::VirtualImageType;
  using typename Superclass::VirtualIndexType;
  using typename Superclass::VirtualPointType;
  using typename Superclass::VirtualPointSetType;

  using typename Superclass::FixedSampledPointSetPointer;
 
  /* Image dimension accessors */
  static constexpr typename TVirtualImage::ImageDimensionType VirtualImageDimension = TVirtualImage::ImageDimension;
  static constexpr typename TFixedImage::ImageDimensionType   FixedImageDimension = TFixedImage::ImageDimension;
  static constexpr typename TMovingImage::ImageDimensionType  MovingImageDimension = TMovingImage::ImageDimension;

  itkSetClampMacro(NumberOfHistogramBins, SizeValueType, 5, NumericTraits<SizeValueType>::max());
  itkGetConstReferenceMacro(NumberOfHistogramBins, SizeValueType);
 
  void
  Initialize() override;

  // NOTE:  floating point precision is not as stable.
  // Double precision proves faster and more robust in real-world testing.
  using PDFValueType = TInternalComputationValueType;

  using JointPDFType = Image<PDFValueType, 2>;
  using JointPDFDerivativesType = Image<PDFValueType, 3>;

  const typename JointPDFType::Pointer
  GetJointPDF() const
  {
    if (this->m_ThreaderJointPDF.empty())
    {
      return typename JointPDFType::Pointer(nullptr);
    }
    return this->m_ThreaderJointPDF[0];
  }

  const typename JointPDFDerivativesType::Pointer
  GetJointPDFDerivatives() const
  {
    return this->m_JointPDFDerivatives;
  }
 
  void
  FinalizeThread(const ThreadIdType threadId) override;
 
protected:
  MattesMutualInformationImageToImageMetricv4();
  ~MattesMutualInformationImageToImageMetricv4() override = default;
 
  friend class MattesMutualInformationImageToImageMetricv4GetValueAndDerivativeThreader<
    ThreadedImageRegionPartitioner<Superclass::VirtualImageDimension>,
    Superclass,
    Self>;
  friend class MattesMutualInformationImageToImageMetricv4GetValueAndDerivativeThreader<
    ThreadedIndexedContainerPartitioner,
    Superclass,
    Self>;
  using MattesMutualInformationDenseGetValueAndDerivativeThreaderType =
    MattesMutualInformationImageToImageMetricv4GetValueAndDerivativeThreader<
      ThreadedImageRegionPartitioner<Superclass::VirtualImageDimension>,
      Superclass,
      Self>;
  using MattesMutualInformationSparseGetValueAndDerivativeThreaderType =
    MattesMutualInformationImageToImageMetricv4GetValueAndDerivativeThreader<ThreadedIndexedContainerPartitioner,
                                                                             Superclass,
                                                                             Self>;
 
  void
  PrintSelf(std::ostream & os, Indent indent) const override;
 
  using JointPDFIndexType = typename JointPDFType::IndexType;
  using JointPDFValueType = typename JointPDFType::PixelType;
  using JointPDFRegionType = typename JointPDFType::RegionType;
  using JointPDFSizeType = typename JointPDFType::SizeType;
  using JointPDFDerivativesIndexType = typename JointPDFDerivativesType::IndexType;
  using JointPDFDerivativesValueType = typename JointPDFDerivativesType::PixelType;
  using JointPDFDerivativesRegionType = typename JointPDFDerivativesType::RegionType;
  using JointPDFDerivativesSizeType = typename JointPDFDerivativesType::SizeType;

  using CubicBSplineFunctionType = BSplineKernelFunction<3, PDFValueType>;
  using CubicBSplineDerivativeFunctionType = BSplineDerivativeKernelFunction<3, PDFValueType>;

  virtual void
  GetValueCommonAfterThreadedExecution();
 
  OffsetValueType
  ComputeSingleFixedImageParzenWindowIndex(const FixedImagePixelType & value) const;

  SizeValueType m_NumberOfHistogramBins{ 50 };
  PDFValueType  m_MovingImageNormalizedMin{};
  PDFValueType  m_FixedImageNormalizedMin{};
  PDFValueType  m_FixedImageTrueMin{};
  PDFValueType  m_FixedImageTrueMax{};
  PDFValueType  m_MovingImageTrueMin{};
  PDFValueType  m_MovingImageTrueMax{};
  PDFValueType  m_FixedImageBinSize{};
  PDFValueType  m_MovingImageBinSize{};

  using PRatioType = PDFValueType;
  using PRatioArrayType = std::vector<PRatioType>;
 
  mutable PRatioArrayType m_PRatioArray{};

  mutable std::vector<OffsetValueType> m_JointPdfIndex1DArray{};

  mutable std::vector<PDFValueType>              m_MovingImageMarginalPDF{};
  mutable std::vector<std::vector<PDFValueType>> m_ThreaderFixedImageMarginalPDF{};

  typename std::vector<typename JointPDFType::Pointer> m_ThreaderJointPDF{};
 
  /* \class DerivativeBufferManager
   * A helper class to manage complexities of minimizing memory
   * needs for mattes mutual information derivative computations
   * per thread.
   *
   * Thread safety note:
   * A separate object is used locally per each thread. Only the members
   * m_ParentJointPDFDerivativesMutexPtr and m_ParentJointPDFDerivatives
   * are shared between threads and access to m_ParentJointPDFDerivatives
   * is controlled with the m_ParentJointPDFDerivativesMutexPtr mutex lock.
   * \ingroup ITKMetricsv4
   */
  class DerivativeBufferManager
  {
    using Self = DerivativeBufferManager;
 
  public:
    /* All these methods are thread safe except ReduceBuffer */
 
    void
    Initialize(size_t                                    maxBufferLength,
               const size_t                              cachedNumberOfLocalParameters,
               std::mutex *                              parentDerivativeMutexPtr,
               typename JointPDFDerivativesType::Pointer parentJointPDFDerivatives);
 
    void
    DoubleBufferSize();
 
    DerivativeBufferManager()
      : m_MemoryBlock(0)
    {}
 
    ~DerivativeBufferManager() = default;
 
    [[nodiscard]] size_t
    GetCachedNumberOfLocalParameters() const
    {
      return this->m_CachedNumberOfLocalParameters;
    }

    void
    CheckAndReduceIfNecessary();

    void
    BlockAndReduce();
 
    // If offset is same as previous offset, then accumulate with previous
    PDFValueType *
    GetNextElementAndAddOffset(const OffsetValueType & offset)
    {
      m_BufferOffsetContainer[m_CurrentFillSize] = offset;
      PDFValueType * PDFBufferForWriting = m_BufferPDFValuesContainer[m_CurrentFillSize];
      ++m_CurrentFillSize;
      return PDFBufferForWriting;
    }

    void
    ReduceBuffer();
 
  private:
    // How many AccumulatorElements used
    size_t m_CurrentFillSize{ 0 };
    // Contiguous chunk of memory for efficiency
    std::vector<PDFValueType> m_MemoryBlock;
    // The (number of lines in the buffer) * (cells per line)
    size_t                       m_MemoryBlockSize;
    std::vector<PDFValueType *>  m_BufferPDFValuesContainer;
    std::vector<OffsetValueType> m_BufferOffsetContainer;
    size_t                       m_CachedNumberOfLocalParameters;
    size_t                       m_MaxBufferSize;
    // Pointer handle to parent version
    std::mutex * m_ParentJointPDFDerivativesMutexPtr;
    // Smart pointer handle to parent version
    typename JointPDFDerivativesType::Pointer m_ParentJointPDFDerivatives;
  };
 
  std::vector<DerivativeBufferManager>      m_ThreaderDerivativeManager{};
  std::mutex                                m_JointPDFDerivativesLock{};
  typename JointPDFDerivativesType::Pointer m_JointPDFDerivatives{};
 
  PDFValueType m_JointPDFSum{};

  mutable std::vector<DerivativeType> m_LocalDerivativeByParzenBin{};
 
private:
  virtual void
  ComputeResults() const;
};
 
} // end namespace itk
 
#ifndef ITK_MANUAL_INSTANTIATION
#  include "itkMattesMutualInformationImageToImageMetricv4.hxx"
#endif
 
#endif