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/*=========================================================================
Program: Insight Segmentation & Registration Toolkit
Module: $RCSfile: itkNormalVectorDiffusionFunction.txx,v $
Language: C++
Date: $Date: 2008-03-03 13:58:45 $
Version: $Revision: 1.8 $
Copyright (c) Insight Software Consortium. All rights reserved.
See ITKCopyright.txt or http://www.itk.org/HTML/Copyright.htm for details.
This software is distributed WITHOUT ANY WARRANTY; without even
the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
PURPOSE. See the above copyright notices for more information.
=========================================================================*/
#ifndef __itkNormalVectorDiffusionFunction_txx_
#define __itkNormalVectorDiffusionFunction_txx_
#include "itkNormalVectorDiffusionFunction.h"
#include "itkNumericTraits.h"
#include "itkVector.h"
namespace itk {
template <class TSparseImageType>
NormalVectorDiffusionFunction <TSparseImageType>
::NormalVectorDiffusionFunction()
{
// check: should some of this be in Initialize?
RadiusType r;
for( unsigned int j = 0; j < ImageDimension; j++ )
{
r[j] = 1;
}
this->SetRadius(r);
this->SetTimeStep(static_cast<TimeStepType> (0.5/ImageDimension));
m_NormalProcessType = 0;
m_ConductanceParameter = NumericTraits<NodeValueType>::Zero;
m_FluxStopConstant = NumericTraits<NodeValueType>::Zero;
}
template <class TSparseImageType>
void
NormalVectorDiffusionFunction <TSparseImageType>
::PrintSelf(std::ostream& os, Indent indent) const
{
Superclass::PrintSelf(os, indent);
os << indent << "NormalProcessType: " << m_NormalProcessType << std::endl;
os << indent << "ConductanceParameter: "<< m_ConductanceParameter << std::endl;
os << indent << "FluxStopConstant: "<< m_FluxStopConstant << std::endl;
}
template <class TSparseImageType>
void
NormalVectorDiffusionFunction <TSparseImageType>
::PrecomputeSparseUpdate( NeighborhoodType &it ) const
{
unsigned int i, j, k;
NodeValueType DotProduct;
NodeType* CenterNode = it.GetCenterPixel();
const NormalVectorType CenterPixel = CenterNode->m_Data;
NodeType *PreviousNode, *OtherNode;
NormalVectorType PreviousPixel;
Vector < NodeValueType, ImageDimension > gradient [ImageDimension];
NormalVectorType PositiveSidePixel[2], NegativeSidePixel[2], flux;
unsigned long stride [ImageDimension];
unsigned long center;
const NeighborhoodScalesType neighborhoodScales = this->ComputeNeighborhoodScales();
for( j = 0; j < ImageDimension; j++ )
{
stride[j] = it.GetStride( (unsigned long) j);
}
center = it.Size() / 2;
for (i=0;i<ImageDimension;i++) // flux offset axis
{
PreviousNode = it.GetPrevious (i);
if (PreviousNode == 0)
{
for( j = 0; j < ImageDimension; j++ )
{
CenterNode->m_Flux[i][j] = NumericTraits<NodeValueType>::Zero;
}
}
else
{
PreviousPixel = PreviousNode->m_Data;
for (j=0;j<ImageDimension;j++) // derivative axis
{
if (i!=j) // compute derivative on a plane
{
// compute differences (j-axis) in line with center pixel
OtherNode = it.GetPrevious (j);
if (OtherNode == 0)
{
NegativeSidePixel[0] = CenterPixel;
}
else
{
NegativeSidePixel[0] = OtherNode->m_Data;
}
OtherNode = it.GetNext (j);
if (OtherNode == 0)
{
PositiveSidePixel[0] = CenterPixel;
}
else
{
PositiveSidePixel[0] = OtherNode->m_Data;
}
// compute derivative (j-axis) offset from center pixel on i-axis
OtherNode = it.GetPixel (center - stride[i] - stride[j]);
if (OtherNode == 0)
{
NegativeSidePixel[1] = PreviousPixel;
}
else
{
NegativeSidePixel[1] = OtherNode->m_Data;
}
OtherNode = it.GetPixel (center - stride[i] + stride[j]);
if (OtherNode == 0)
{
PositiveSidePixel[1] = PreviousPixel;
}
else
{
PositiveSidePixel[1] = OtherNode->m_Data;
}
gradient[j] = ( ( PositiveSidePixel[0]+PositiveSidePixel[1] )-
( NegativeSidePixel[0]+NegativeSidePixel[1] ) )*
static_cast<NodeValueType>(0.25) * neighborhoodScales[j];
}
else // compute derivative on a line
{
gradient[i] = ( CenterPixel-PreviousPixel ) * neighborhoodScales[i];
}
} // end derivative axis
// now compute the intrinsic derivative
for (j = 0; j < ImageDimension; j++) // component axis
{
DotProduct = NumericTraits<NodeValueType>::Zero;
for (k = 0; k < ImageDimension; k++) // derivative axis
{
DotProduct += (gradient[k][j]*CenterNode->m_ManifoldNormal[i][k]);
}
flux[j] = gradient[i][j]-CenterNode->m_ManifoldNormal[i][i]*DotProduct;
}
// do following line for non-intrinsic derivative
//flux = gradient[i];
if (m_NormalProcessType == 1)
{
// anisotropic diffusion
CenterNode->m_Flux[i] =
flux * this->FluxStopFunction(flux.GetSquaredNorm());
}
else
{
// isotropic diffusion
CenterNode->m_Flux[i] = flux;
}
} // end if-else PreviousNode==0
} // end flux offset axis
}
template <class TSparseImageType>
typename NormalVectorDiffusionFunction <TSparseImageType>::NormalVectorType
NormalVectorDiffusionFunction <TSparseImageType>
::ComputeSparseUpdate( NeighborhoodType &it,
void*, const FloatOffsetType& ) const
{
unsigned int i;
NormalVectorType change;
NodeValueType DotProduct;
const NodeType* CenterNode = it.GetCenterPixel();
const NormalVectorType CenterPixel = CenterNode->m_Data;
NodeType* NextNode;
const NeighborhoodScalesType neighborhoodScales = this->ComputeNeighborhoodScales();
change = NumericTraits<NormalVectorType>::Zero;
for (i=0;i<ImageDimension;i++) // flux offset axis
{
NextNode = it.GetNext (i);
if (NextNode == 0)
{
change -= CenterNode->m_Flux[i] * neighborhoodScales[i];
}
else
{
change += ( NextNode->m_Flux[i] - CenterNode->m_Flux[i]) * neighborhoodScales[i];
}
} // end flux offset axis
DotProduct = change*CenterPixel;
change -= CenterPixel*DotProduct;
return change;
}
} // end namespace itk
#endif
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