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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 itkFastMarchingUpwindGradientImageFilterBase_hxx
#define itkFastMarchingUpwindGradientImageFilterBase_hxx
#include "itkFastMarchingUpwindGradientImageFilterBase.h"
#include "itkImageRegionIterator.h"
#include "itkNumericTraits.h"
#include "itkMath.h"
#include <algorithm>
namespace itk
{
/**
*
*/
template< typename TInput, typename TOutput >
FastMarchingUpwindGradientImageFilterBase< TInput, TOutput >
::FastMarchingUpwindGradientImageFilterBase()
{
GradientImagePointer GradientImage = GradientImageType::New();
this->SetNthOutput( 1, GradientImage.GetPointer() );
}
template< typename TInput, typename TOutput >
typename FastMarchingUpwindGradientImageFilterBase< TInput, TOutput >::GradientImageType*
FastMarchingUpwindGradientImageFilterBase< TInput, TOutput >
::GetGradientImage()
{
return dynamic_cast< GradientImageType* >( this->ProcessObject::GetOutput( 1 ) );
}
/**
*
*/
template< typename TInput, typename TOutput >
void
FastMarchingUpwindGradientImageFilterBase< TInput, TOutput >
::PrintSelf(std::ostream & os, Indent indent) const
{
Superclass::PrintSelf(os, indent);
}
/**
*
*/
template< typename TInput, typename TOutput >
void
FastMarchingUpwindGradientImageFilterBase< TInput, TOutput >::
InitializeOutput(OutputImageType *output)
{
Superclass::InitializeOutput(output);
// allocate memory for the GradientImage if requested
GradientImagePointer GradientImage = this->GetGradientImage();
GradientImage->CopyInformation( this->GetInput() );
GradientImage->SetBufferedRegion( output->GetBufferedRegion() );
GradientImage->Allocate();
typedef ImageRegionIterator< GradientImageType > GradientIterator;
GradientIterator gradientIt( GradientImage,
GradientImage->GetBufferedRegion() );
GradientPixelType zeroGradient;
typedef typename GradientPixelType::ValueType GradientPixelValueType;
zeroGradient.Fill(NumericTraits< GradientPixelValueType >::ZeroValue());
gradientIt.GoToBegin();
while( !gradientIt.IsAtEnd() )
{
gradientIt.Set(zeroGradient);
++gradientIt;
}
}
template< typename TInput, typename TOutput >
void
FastMarchingUpwindGradientImageFilterBase< TInput, TOutput >::
UpdateNeighbors(
OutputImageType* oImage,
const NodeType& iNode )
{
Superclass::UpdateNeighbors( oImage, iNode );
this->ComputeGradient( oImage, iNode );
}
/**
*
*/
template< typename TInput, typename TOutput >
void
FastMarchingUpwindGradientImageFilterBase< TInput, TOutput >
::ComputeGradient( OutputImageType* oImage,
const NodeType& iNode )
{
NodeType neighIndex = iNode;
OutputPixelType centerPixel;
OutputPixelType dx_forward;
OutputPixelType dx_backward;
GradientPixelType gradientPixel;
const OutputPixelType ZERO = NumericTraits< OutputPixelType >::ZeroValue();
OutputSpacingType spacing = oImage->GetSpacing();
unsigned int xStride[ itkGetStaticConstMacro( ImageDimension ) ];
centerPixel = oImage->GetPixel( iNode );
for ( unsigned int j = 0; j < ImageDimension; j++ )
{
neighIndex = iNode;
// Set stride of one in each direction
xStride[j] = 1;
// Compute one-sided finite differences with alive neighbors
// (the front can only come from there)
dx_backward = ZERO;
neighIndex[j] = iNode[j] - xStride[j];
if ( !( ( neighIndex[j] > this->m_LastIndex[j] ) ||
( neighIndex[j] < this->m_StartIndex[j] ) ) )
{
if ( this->GetLabelValueForGivenNode(neighIndex) == Traits::Alive )
{
dx_backward = centerPixel - oImage->GetPixel(neighIndex);
}
}
dx_forward = ZERO;
neighIndex[j] = iNode[j] + xStride[j];
if ( !( ( neighIndex[j] > this->m_LastIndex[j] ) ||
( neighIndex[j] < this->m_StartIndex[j] ) ) )
{
if ( this->GetLabelValueForGivenNode(neighIndex) == Traits::Alive )
{
dx_forward = oImage->GetPixel(neighIndex) - centerPixel;
}
}
// Compute upwind finite differences
if ( std::max(dx_backward, -dx_forward) < ZERO )
{
gradientPixel[j] = ZERO;
}
else
{
if ( dx_backward > -dx_forward )
{
gradientPixel[j] = dx_backward;
}
else
{
gradientPixel[j] = dx_forward;
}
}
gradientPixel[j] /= spacing[j];
}
GradientImagePointer GradientImage = this->GetGradientImage();
GradientImage->SetPixel(iNode, gradientPixel);
}
} // namespace itk
#endif
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