itkWeightedAddImageFilter.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 itkWeightedAddImageFilter_h
#define itkWeightedAddImageFilter_h
 
#include "itkBinaryGeneratorImageFilter.h"
#include "itkNumericTraits.h"
#include "itkMath.h"
 
namespace itk
{
namespace Functor
{
template <typename TInput1, typename TInput2, typename TOutput>
class WeightedAdd2
{
public:
  using AccumulatorType = typename NumericTraits<TInput1>::AccumulateType;
  using RealType = typename NumericTraits<TInput1>::RealType;
  WeightedAdd2()
    : m_Alpha(0.0)
    , m_Beta(0.0)
  {}
  ~WeightedAdd2() = default;
 
  bool
  operator==(const WeightedAdd2 & other) const
  {
    return Math::ExactlyEquals(m_Alpha, other.m_Alpha);
  }
 
  ITK_UNEQUAL_OPERATOR_MEMBER_FUNCTION(WeightedAdd2);
 
  inline TOutput
  operator()(const TInput1 & A, const TInput2 & B) const
  {
    const RealType sum1 = A * m_Alpha;
    const RealType sum2 = B * m_Beta;
 
    return static_cast<TOutput>(sum1 + sum2);
  }
 
  void
  SetAlpha(RealType alpha)
  {
    m_Alpha = alpha;
    m_Beta = NumericTraits<RealType>::OneValue() - m_Alpha;
  }
 
  [[nodiscard]] RealType
  GetAlpha() const
  {
    return m_Alpha;
  }
 
private:
  RealType m_Alpha;
  RealType m_Beta; // auxiliary var to avoid a subtraction at every pixel
};
} // namespace Functor

template <typename TInputImage1, typename TInputImage2, typename TOutputImage>
class ITK_TEMPLATE_EXPORT WeightedAddImageFilter
  : public BinaryGeneratorImageFilter<TInputImage1, TInputImage2, TOutputImage>
{
public:
  ITK_DISALLOW_COPY_AND_MOVE(WeightedAddImageFilter);

  using Self = WeightedAddImageFilter;
  using Superclass = BinaryGeneratorImageFilter<TInputImage1, TInputImage2, TOutputImage>;
 
 
  using FunctorType = Functor::
    WeightedAdd2<typename TInputImage1::PixelType, typename TInputImage2::PixelType, typename TOutputImage::PixelType>;
 
  using Pointer = SmartPointer<Self>;
  using ConstPointer = SmartPointer<const Self>;
 
  using RealType = typename FunctorType::RealType;

  itkNewMacro(Self);

  itkOverrideGetNameOfClassMacro(WeightedAddImageFilter);

  void
  SetAlpha(RealType alpha)
  {
    this->GetFunctor().SetAlpha(alpha);
    this->Modified();
  }

  RealType
  GetAlpha() const
  {
    return this->GetFunctor().GetAlpha();
  }
 
  itkConceptMacro(Input1HasNumericTraitsCheck, (Concept::HasNumericTraits<typename TInputImage1::PixelType>));
  itkConceptMacro(Input1RealTypeMultiplyCheck,
                  (Concept::MultiplyOperator<typename TInputImage1::PixelType, RealType, RealType>));
  itkConceptMacro(Input2RealTypeMultiplyCheck,
                  (Concept::MultiplyOperator<typename TInputImage2::PixelType, RealType, RealType>));
 
protected:
  WeightedAddImageFilter() = default;
  ~WeightedAddImageFilter() override = default;
 
  void
  BeforeThreadedGenerateData() override
  {
    this->SetFunctor(this->GetFunctor());
  }
 
private:
  itkGetConstReferenceMacro(Functor, FunctorType);
  FunctorType &
  GetFunctor()
  {
    return m_Functor;
  }
 
  FunctorType m_Functor{};
};
} // end namespace itk
 
#endif