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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 itkMedianImageFilter_hxx
#define itkMedianImageFilter_hxx
#include "itkBufferedImageNeighborhoodPixelAccessPolicy.h"
#include "itkImageNeighborhoodOffsets.h"
#include "itkImageRegionRange.h"
#include "itkIndexRange.h"
#include "itkNeighborhoodAlgorithm.h"
#include "itkOffset.h"
#include "itkShapedImageNeighborhoodRange.h"
#include "itkTotalProgressReporter.h"
#include <vector>
#include <algorithm>
namespace itk
{
template <typename TInputImage, typename TOutputImage>
MedianImageFilter<TInputImage, TOutputImage>::MedianImageFilter()
{
this->DynamicMultiThreadingOn();
this->ThreaderUpdateProgressOff();
}
template <typename TInputImage, typename TOutputImage>
void
MedianImageFilter<TInputImage, TOutputImage>::DynamicThreadedGenerateData(
const OutputImageRegionType & outputRegionForThread)
{
// Allocate output
OutputImageType * output = this->GetOutput();
const InputImageType * input = this->GetInput();
const auto radius = this->GetRadius();
// Find the data-set boundary "faces" and the center non-boundary subregion.
const auto calculatorResult =
NeighborhoodAlgorithm::ImageBoundaryFacesCalculator<InputImageType>::Compute(*input, outputRegionForThread, radius);
const auto neighborhoodOffsets = GenerateRectangularImageNeighborhoodOffsets<InputImageDimension>(radius);
const auto neighborhoodSize = neighborhoodOffsets.size();
// All of our neighborhoods have an odd number of pixels, so there is
// always a median.
std::vector<InputPixelType> pixels(neighborhoodSize);
const auto medianIterator = pixels.begin() + (neighborhoodSize / 2);
TotalProgressReporter progress(this, output->GetRequestedRegion().GetNumberOfPixels());
const auto nonBoundaryRegion = calculatorResult.GetNonBoundaryRegion();
if (!nonBoundaryRegion.GetSize().empty())
{
// Process the non-boundary subregion, using a faster pixel access policy without boundary extrapolation.
auto neighborhoodRange =
ShapedImageNeighborhoodRange<const InputImageType, BufferedImageNeighborhoodPixelAccessPolicy<InputImageType>>(
*input, Index<InputImageDimension>(), neighborhoodOffsets);
auto outputIterator = ImageRegionRange<OutputImageType>(*output, nonBoundaryRegion).begin();
for (const auto & index : ImageRegionIndexRange<InputImageDimension>(nonBoundaryRegion))
{
neighborhoodRange.SetLocation(index);
std::copy_n(neighborhoodRange.cbegin(), neighborhoodSize, pixels.begin());
std::nth_element(pixels.begin(), medianIterator, pixels.end());
*outputIterator = *medianIterator;
++outputIterator;
progress.CompletedPixel();
}
}
// Process each of the boundary faces. These are N-d regions which border
// the edge of the buffer.
for (const auto & boundaryFace : calculatorResult.GetBoundaryFaces())
{
auto neighborhoodRange =
ShapedImageNeighborhoodRange<const InputImageType>(*input, Index<InputImageDimension>(), neighborhoodOffsets);
auto outputIterator = ImageRegionRange<OutputImageType>(*output, boundaryFace).begin();
for (const auto & index : ImageRegionIndexRange<InputImageDimension>(boundaryFace))
{
neighborhoodRange.SetLocation(index);
std::copy_n(neighborhoodRange.cbegin(), neighborhoodSize, pixels.begin());
std::nth_element(pixels.begin(), medianIterator, pixels.end());
*outputIterator = *medianIterator;
++outputIterator;
progress.CompletedPixel();
}
}
}
} // end namespace itk
#endif
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