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/*========================================================================= |
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Program: Insight Segmentation & Registration Toolkit |
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Module: $RCSfile: itkVarianceImageFunction.txx.html,v $ |
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Language: C++ |
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Date: $Date: 2006/01/17 19:15:49 $ |
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Version: $Revision: 1.4 $ |
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Copyright (c) Insight Software Consortium. All rights reserved. |
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See ITKCopyright.txt or http://www.itk.org/HTML/Copyright.htm for details. |
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This software is distributed WITHOUT ANY WARRANTY; without even |
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the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR |
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PURPOSE. See the above copyright notices for more information. |
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=========================================================================*/ |
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DEF |
#ifndef _itkVarianceImageFunction_txx |
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DEF |
#define _itkVarianceImageFunction_txx |
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#include "itkVarianceImageFunction.h" |
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#include "itkNumericTraits.h" |
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#include "itkConstNeighborhoodIterator.h" |
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namespace itk |
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{ |
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/** |
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* Constructor |
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*/ |
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template <class TInputImage, class TCoordRep> |
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VarianceImageFunction<TInputImage,TCoordRep> |
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::VarianceImageFunction() |
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{ |
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m_NeighborhoodRadius = 1; |
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} |
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/** |
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* |
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*/ |
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template <class TInputImage, class TCoordRep> |
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void |
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VarianceImageFunction<TInputImage,TCoordRep> |
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::PrintSelf(std::ostream& os, Indent indent) const |
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{ |
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this->Superclass::PrintSelf(os,indent); |
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os << indent << "NeighborhoodRadius: " << m_NeighborhoodRadius << std::endl; |
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} |
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/** |
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* |
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*/ |
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template <class TInputImage, class TCoordRep> |
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typename VarianceImageFunction<TInputImage,TCoordRep> |
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::RealType |
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VarianceImageFunction<TInputImage,TCoordRep> |
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::EvaluateAtIndex(const IndexType& index) const |
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{ |
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RealType sum; |
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RealType sumOfSquares; |
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RealType var; |
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sum = NumericTraits<RealType>::Zero; |
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sumOfSquares = NumericTraits<RealType>::Zero; |
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if( !this->GetInputImage() ) |
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{ |
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return ( NumericTraits<RealType>::max() ); |
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} |
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if ( !this->IsInsideBuffer( index ) ) |
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{ |
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return ( NumericTraits<RealType>::max() ); |
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} |
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// Create an N-d neighborhood kernel, using a zeroflux boundary condition |
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typename InputImageType::SizeType kernelSize; |
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kernelSize.Fill( m_NeighborhoodRadius ); |
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ConstNeighborhoodIterator<InputImageType> |
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LEN,IND |
****it(kernelSize, this->GetInputImage(), this->GetInputImage()->GetBufferedRegion()); |
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// Set the iterator at the desired location |
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it.SetLocation(index); |
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// Walk the neighborhood |
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const unsigned int size = it.Size(); |
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for (unsigned int i = 0; i < size; ++i) |
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{ |
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const RealType value = static_cast<RealType>( it.GetPixel(i) ); |
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sum += value; |
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sumOfSquares += value * value; |
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} |
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const double num = static_cast<double>( size ); |
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var = ( sumOfSquares - ( sum*sum / num ) ) / ( num - 1.0 ); |
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return ( var ); |
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} |
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} // namespace itk |
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#endif |
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