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itkVarianceImageFunction.txx
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itkVarianceImageFunction.txx
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/*=========================================================================
Program: Insight Segmentation & Registration Toolkit
Module: itkVarianceImageFunction.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 __itkVarianceImageFunction_txx
#define __itkVarianceImageFunction_txx
#include "itkVarianceImageFunction.h"
#include "itkNumericTraits.h"
#include "itkConstNeighborhoodIterator.h"
namespace itk
{
/**
* Constructor
*/
template <class TInputImage, class TCoordRep>
VarianceImageFunction<TInputImage,TCoordRep>
::VarianceImageFunction()
{
m_NeighborhoodRadius = 1;
}
/**
*
*/
template <class TInputImage, class TCoordRep>
void
VarianceImageFunction<TInputImage,TCoordRep>
::PrintSelf(std::ostream& os, Indent indent) const
{
this->Superclass::PrintSelf(os,indent);
os << indent << "NeighborhoodRadius: " << m_NeighborhoodRadius << std::endl;
}
/**
*
*/
template <class TInputImage, class TCoordRep>
typename VarianceImageFunction<TInputImage,TCoordRep>
::RealType
VarianceImageFunction<TInputImage,TCoordRep>
::EvaluateAtIndex(const IndexType& index) const
{
RealType sum;
RealType sumOfSquares;
RealType var;
sum = NumericTraits<RealType>::Zero;
sumOfSquares = NumericTraits<RealType>::Zero;
if( !this->GetInputImage() )
{
return ( NumericTraits<RealType>::max() );
}
if ( !this->IsInsideBuffer( index ) )
{
return ( NumericTraits<RealType>::max() );
}
// Create an N-d neighborhood kernel, using a zeroflux boundary condition
typename InputImageType::SizeType kernelSize;
kernelSize.Fill( m_NeighborhoodRadius );
ConstNeighborhoodIterator<InputImageType>
it(kernelSize, this->GetInputImage(), this->GetInputImage()->GetBufferedRegion());
// Set the iterator at the desired location
it.SetLocation(index);
// Walk the neighborhood
const unsigned int size = it.Size();
for (unsigned int i = 0; i < size; ++i)
{
const RealType value = static_cast<RealType>( it.GetPixel(i) );
sum += value;
sumOfSquares += value * value;
}
const double num = static_cast<double>( size );
var = ( sumOfSquares - ( sum*sum / num ) ) / ( num - 1.0 );
return ( var );
}
} // end namespace itk
#endif