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itkCentralDifferenceImageFunction.txx
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itkCentralDifferenceImageFunction.txx
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/*=========================================================================
Program: Insight Segmentation & Registration Toolkit
Module: itkCentralDifferenceImageFunction.txx
Language: C++
Date: $Date$
Version: $Revision$
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 __itkCentralDifferenceImageFunction_txx
#define __itkCentralDifferenceImageFunction_txx
#include "itkCentralDifferenceImageFunction.h"
namespace itk
{
/**
* Constructor
*/
template <class TInputImage, class TCoordRep>
CentralDifferenceImageFunction<TInputImage,TCoordRep>
::CentralDifferenceImageFunction()
{
this->m_UseImageDirection = true;
}
/**
*
*/
template <class TInputImage, class TCoordRep>
void
CentralDifferenceImageFunction<TInputImage,TCoordRep>
::PrintSelf(std::ostream& os, Indent indent) const
{
this->Superclass::PrintSelf(os,indent);
os << indent << "UseImageDirection = " << this->m_UseImageDirection << std::endl;
}
/**
*
*/
template <class TInputImage, class TCoordRep>
typename CentralDifferenceImageFunction<TInputImage,TCoordRep>::OutputType
CentralDifferenceImageFunction<TInputImage,TCoordRep>
::EvaluateAtIndex( const IndexType& index ) const
{
OutputType derivative;
derivative.Fill( 0.0 );
IndexType neighIndex = index;
const InputImageType * inputImage = this->GetInputImage();
const typename InputImageType::RegionType region =
inputImage->GetBufferedRegion();
const typename InputImageType::SizeType& size = region.GetSize();
const typename InputImageType::IndexType& start = region.GetIndex();
for ( unsigned int dim = 0; dim < TInputImage::ImageDimension; dim++ )
{
// bounds checking
if( index[dim] < static_cast<long>(start[dim]) + 1 ||
index[dim] > (start[dim] + static_cast<long>(size[dim]) - 2 ) )
{
derivative[dim] = 0.0;
continue;
}
// compute derivative
neighIndex[dim] += 1;
derivative[dim] = inputImage->GetPixel( neighIndex );
neighIndex[dim] -= 2;
derivative[dim] -= inputImage->GetPixel( neighIndex );
derivative[dim] *= 0.5 / inputImage->GetSpacing()[dim];
neighIndex[dim] += 1;
}
if( this->m_UseImageDirection )
{
OutputType orientedDerivative;
inputImage->TransformLocalVectorToPhysicalVector( derivative, orientedDerivative );
return orientedDerivative;
}
return ( derivative );
}
} // end namespace itk
#endif