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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 itkThresholdSegmentationLevelSetFunction_hxx
#define itkThresholdSegmentationLevelSetFunction_hxx
#include "itkImageRegionIterator.h"
#include "itkGradientAnisotropicDiffusionImageFilter.h"
#include "itkLaplacianImageFilter.h"
namespace itk
{
template <typename TImageType, typename TFeatureImageType>
void
ThresholdSegmentationLevelSetFunction<TImageType, TFeatureImageType>::CalculateSpeedImage()
{
typename GradientAnisotropicDiffusionImageFilter<TFeatureImageType, TFeatureImageType>::Pointer diffusion =
GradientAnisotropicDiffusionImageFilter<TFeatureImageType, TFeatureImageType>::New();
typename LaplacianImageFilter<TFeatureImageType, TFeatureImageType>::Pointer laplacian =
LaplacianImageFilter<TFeatureImageType, TFeatureImageType>::New();
ImageRegionIterator<FeatureImageType> lit;
ImageRegionConstIterator<FeatureImageType> fit(this->GetFeatureImage(),
this->GetFeatureImage()->GetRequestedRegion());
ImageRegionIterator<ImageType> sit(this->GetSpeedImage(), this->GetFeatureImage()->GetRequestedRegion());
if (m_EdgeWeight != 0.0)
{
diffusion->SetInput(this->GetFeatureImage());
diffusion->SetConductanceParameter(m_SmoothingConductance);
diffusion->SetTimeStep(m_SmoothingTimeStep);
diffusion->SetNumberOfIterations(m_SmoothingIterations);
laplacian->SetInput(diffusion->GetOutput());
laplacian->Update();
lit = ImageRegionIterator<FeatureImageType>(laplacian->GetOutput(), this->GetFeatureImage()->GetRequestedRegion());
lit.GoToBegin();
}
// Copy the meta information (spacing and origin) from the feature image
this->GetSpeedImage()->CopyInformation(this->GetFeatureImage());
// Calculate the speed image
auto upper_threshold = static_cast<ScalarValueType>(m_UpperThreshold);
auto lower_threshold = static_cast<ScalarValueType>(m_LowerThreshold);
ScalarValueType mid = ((upper_threshold - lower_threshold) / 2.0) + lower_threshold;
ScalarValueType threshold;
for (fit.GoToBegin(), sit.GoToBegin(); !fit.IsAtEnd(); ++sit, ++fit)
{
if (static_cast<ScalarValueType>(fit.Get()) < mid)
{
threshold = fit.Get() - lower_threshold;
}
else
{
threshold = upper_threshold - fit.Get();
}
if (m_EdgeWeight != 0.0)
{
sit.Set(static_cast<ScalarValueType>(threshold + m_EdgeWeight * lit.Get()));
++lit;
}
else
{
sit.Set(static_cast<ScalarValueType>(threshold));
}
}
}
} // end namespace itk
#endif
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