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/*=========================================================================
*
* Copyright Insight Software Consortium
*
* 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 itkHessian3DToVesselnessMeasureImageFilter_hxx
#define itkHessian3DToVesselnessMeasureImageFilter_hxx
#include "itkHessian3DToVesselnessMeasureImageFilter.h"
#include "itkImageRegionIterator.h"
#include "itkMath.h"
namespace itk
{
/**
* Constructor
*/
template< typename TPixel >
Hessian3DToVesselnessMeasureImageFilter< TPixel >
::Hessian3DToVesselnessMeasureImageFilter()
{
m_Alpha1 = 0.5;
m_Alpha2 = 2.0;
// Hessian( Image ) = Jacobian( Gradient ( Image ) ) is symmetric
m_SymmetricEigenValueFilter = EigenAnalysisFilterType::New();
m_SymmetricEigenValueFilter->SetDimension(ImageDimension);
m_SymmetricEigenValueFilter->OrderEigenValuesBy(
EigenAnalysisFilterType::FunctorType::OrderByValue);
}
template< typename TPixel >
void
Hessian3DToVesselnessMeasureImageFilter< TPixel >
::GenerateData()
{
itkDebugMacro(<< "Hessian3DToVesselnessMeasureImageFilter generating data ");
m_SymmetricEigenValueFilter->SetInput( this->GetInput() );
typename OutputImageType::Pointer output = this->GetOutput();
typedef typename EigenAnalysisFilterType::OutputImageType
EigenValueOutputImageType;
m_SymmetricEigenValueFilter->Update();
const typename EigenValueOutputImageType::ConstPointer eigenImage =
m_SymmetricEigenValueFilter->GetOutput();
// walk the region of eigen values and get the vesselness measure
EigenValueArrayType eigenValue;
ImageRegionConstIterator< EigenValueOutputImageType > it;
it = ImageRegionConstIterator< EigenValueOutputImageType >(
eigenImage, eigenImage->GetRequestedRegion() );
ImageRegionIterator< OutputImageType > oit;
this->AllocateOutputs();
oit = ImageRegionIterator< OutputImageType >( output,
output->GetRequestedRegion() );
oit.GoToBegin();
it.GoToBegin();
while ( !it.IsAtEnd() )
{
// Get the eigen value
eigenValue = it.Get();
// normalizeValue <= 0 for bright line structures
double normalizeValue = std::min(-1.0 * eigenValue[1], -1.0 * eigenValue[0]);
// Similarity measure to a line structure
if ( normalizeValue > 0 )
{
double lineMeasure;
if ( eigenValue[2] <= 0 )
{
lineMeasure =
std::exp( -0.5 * itk::Math::sqr( eigenValue[2] / ( m_Alpha1 * normalizeValue ) ) );
}
else
{
lineMeasure =
std::exp( -0.5 * itk::Math::sqr( eigenValue[2] / ( m_Alpha2 * normalizeValue ) ) );
}
lineMeasure *= normalizeValue;
oit.Set( static_cast< OutputPixelType >( lineMeasure ) );
}
else
{
oit.Set(NumericTraits< OutputPixelType >::ZeroValue());
}
++it;
++oit;
}
}
template< typename TPixel >
void
Hessian3DToVesselnessMeasureImageFilter< TPixel >
::PrintSelf(std::ostream & os, Indent indent) const
{
Superclass::PrintSelf(os, indent);
os << indent << "Alpha1: " << m_Alpha1 << std::endl;
os << indent << "Alpha2: " << m_Alpha2 << std::endl;
}
} // end namespace itk
#endif
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