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itkMeanSquareRegistrationFunction.hxx
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itkMeanSquareRegistrationFunction.hxx
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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
*
* http://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 itkMeanSquareRegistrationFunction_hxx
#define itkMeanSquareRegistrationFunction_hxx
#include "itkMacro.h"
#include "itkMath.h"
#include "itkMath.h"
namespace itk
{
/**
* Default constructor
*/
template <typename TFixedImage, typename TMovingImage, typename TDisplacementField>
MeanSquareRegistrationFunction<TFixedImage, TMovingImage, TDisplacementField>::MeanSquareRegistrationFunction()
{
RadiusType r;
unsigned int j;
for (j = 0; j < ImageDimension; ++j)
{
r[j] = 0;
}
this->SetRadius(r);
this->SetEnergy(0.0);
m_TimeStep = 1.0;
m_DenominatorThreshold = 1e-9;
m_IntensityDifferenceThreshold = 0.001;
this->SetMovingImage(nullptr);
this->SetFixedImage(nullptr);
m_FixedImageGradientCalculator = GradientCalculatorType::New();
auto interp = DefaultInterpolatorType::New();
m_MovingImageInterpolator = itkDynamicCastInDebugMode<InterpolatorType *>(interp.GetPointer());
}
/*
* Standard "PrintSelf" method.
*/
template <typename TFixedImage, typename TMovingImage, typename TDisplacementField>
void
MeanSquareRegistrationFunction<TFixedImage, TMovingImage, TDisplacementField>::PrintSelf(std::ostream & os,
Indent indent) const
{
Superclass::PrintSelf(os, indent);
/*
os << indent << "MovingImageIterpolator: ";
os << m_MovingImageInterpolator.GetPointer() << std::endl;
os << indent << "FixedImageGradientCalculator: ";
os << m_FixedImageGradientCalculator.GetPointer() << std::endl;
os << indent << "DenominatorThreshold: ";
os << m_DenominatorThreshold << std::endl;
os << indent << "IntensityDifferenceThreshold: ";
os << m_IntensityDifferenceThreshold << std::endl;
*/
}
/*
* Set the function state values before each iteration
*/
template <typename TFixedImage, typename TMovingImage, typename TDisplacementField>
void
MeanSquareRegistrationFunction<TFixedImage, TMovingImage, TDisplacementField>::InitializeIteration()
{
if (!this->GetMovingImage() || !this->GetFixedImage() || !m_MovingImageInterpolator)
{
itkExceptionMacro(<< "MovingImage, FixedImage and/or Interpolator not set");
}
// cache fixed image information
m_FixedImageSpacing = this->GetFixedImage()->GetSpacing();
// setup gradient calculator
m_FixedImageGradientCalculator->SetInputImage(this->GetFixedImage());
// setup moving image interpolator
m_MovingImageInterpolator->SetInputImage(this->GetMovingImage());
this->SetEnergy(0.0);
}
/**
* Compute update at a non boundary neighbourhood
*/
template <typename TFixedImage, typename TMovingImage, typename TDisplacementField>
typename MeanSquareRegistrationFunction<TFixedImage, TMovingImage, TDisplacementField>::PixelType
MeanSquareRegistrationFunction<TFixedImage, TMovingImage, TDisplacementField>::ComputeUpdate(
const NeighborhoodType & it,
void * itkNotUsed(globalData),
const FloatOffsetType & itkNotUsed(offset))
{
// Get fixed image related information
// Note: no need to check the index is within
// fixed image buffer. This is done by the external filter.
const IndexType index = it.GetIndex();
const auto fixedValue = (double)this->GetFixedImage()->GetPixel(index);
const CovariantVectorType fixedGradient = m_FixedImageGradientCalculator->EvaluateAtIndex(index);
double fixedGradientSquaredMagnitude = 0;
for (unsigned int j = 0; j < ImageDimension; ++j)
{
fixedGradientSquaredMagnitude += itk::Math::sqr(fixedGradient[j]) * m_FixedImageSpacing[j];
}
// Get moving image related information
const DisplacementFieldPixelType itvec = this->GetDisplacementField()->GetPixel(index);
PointType mappedPoint;
this->GetFixedImage()->TransformIndexToPhysicalPoint(index, mappedPoint);
for (unsigned int j = 0; j < ImageDimension; ++j)
{
mappedPoint[j] += itvec[j];
}
double movingValue = 0.0;
if (m_MovingImageInterpolator->IsInsideBuffer(mappedPoint))
{
movingValue = m_MovingImageInterpolator->Evaluate(mappedPoint);
}
// Compute update
const double speedValue = fixedValue - movingValue;
this->m_Energy += speedValue * speedValue;
const bool normalizemetric = this->GetNormalizeGradient();
double denominator = 1.0;
if (normalizemetric)
{
denominator = speedValue * speedValue * fixedGradientSquaredMagnitude;
denominator = std::sqrt(denominator);
}
if (Math::AlmostEquals(denominator, 0.0))
{
denominator = 1.0;
}
PixelType update;
if (itk::Math::abs(speedValue) < m_IntensityDifferenceThreshold || denominator < m_DenominatorThreshold)
{
update.Fill(0.0);
return update;
}
for (unsigned int j = 0; j < ImageDimension; ++j)
{
update[j] =
speedValue * fixedGradient[j] * itk::Math::sqr(m_FixedImageSpacing[j]) / denominator * this->m_GradientStep;
}
return update;
}
} // end namespace itk
#endif