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/*=========================================================================
*
* Copyright NumFOCUS
*
* 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
*
* https://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 itkVectorCentralDifferenceImageFunction_hxx
#define itkVectorCentralDifferenceImageFunction_hxx
namespace itk
{
template <typename TInputImage, typename TCoordRep>
VectorCentralDifferenceImageFunction<TInputImage, TCoordRep>::VectorCentralDifferenceImageFunction()
{}
template <typename TInputImage, typename TCoordRep>
void
VectorCentralDifferenceImageFunction<TInputImage, TCoordRep>::PrintSelf(std::ostream & os, Indent indent) const
{
this->Superclass::PrintSelf(os, indent);
os << indent << "UseImageDirection: " << m_UseImageDirection << std::endl;
}
template <typename TInputImage, typename TCoordRep>
auto
VectorCentralDifferenceImageFunction<TInputImage, TCoordRep>::EvaluateAtIndex(const IndexType & index) const
-> OutputType
{
OutputType derivative;
derivative.Fill(0.0);
IndexType neighIndex = index;
const typename InputImageType::SizeType & size = this->GetInputImage()->GetBufferedRegion().GetSize();
const typename InputImageType::IndexType & start = this->GetInputImage()->GetBufferedRegion().GetIndex();
for (unsigned int dim = 0; dim < TInputImage::ImageDimension; ++dim)
{
// bounds checking
if (index[dim] < start[dim] + 1 || index[dim] > (start[dim] + static_cast<OffsetValueType>(size[dim]) - 2))
{
for (unsigned int vdim = 0; vdim < Dimension; ++vdim)
{
derivative(vdim, dim) = 0.0;
}
continue;
}
// compute derivative
const double deriv_weight = 0.5 / this->GetInputImage()->GetSpacing()[dim];
neighIndex[dim] += 1;
const InputPixelType & pixf = this->GetInputImage()->GetPixel(neighIndex);
for (unsigned int vdim = 0; vdim < Dimension; ++vdim)
{
derivative(vdim, dim) = pixf[vdim];
}
neighIndex[dim] -= 2;
const InputPixelType & pixb = this->GetInputImage()->GetPixel(neighIndex);
for (unsigned int vdim = 0; vdim < Dimension; ++vdim)
{
derivative(vdim, dim) -= pixb[vdim];
derivative(vdim, dim) *= deriv_weight;
}
neighIndex[dim] += 1;
}
if (this->m_UseImageDirection)
{
OutputType orientedderivative;
const typename InputImageType::DirectionType & direction = this->GetInputImage()->GetDirection();
for (unsigned int i = 0; i < TInputImage::ImageDimension; ++i)
{
std::vector<double> sums(Dimension, 0.0);
for (unsigned int j = 0; j < TInputImage::ImageDimension; ++j)
{
for (unsigned int vdim = 0; vdim < Dimension; ++vdim)
{
sums[vdim] += direction[i][j] * derivative(vdim, j);
}
}
for (unsigned int vdim = 0; vdim < Dimension; ++vdim)
{
orientedderivative(vdim, i) = static_cast<TCoordRep>(sums[vdim]);
}
}
return orientedderivative;
}
return (derivative);
}
} // end namespace itk
#endif
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