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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.
*
*=========================================================================*/
/*=========================================================================
*
* Portions of this file are subject to the VTK Toolkit Version 3 copyright.
*
* Copyright (c) Ken Martin, Will Schroeder, Bill Lorensen
*
* For complete copyright, license and disclaimer of warranty information
* please refer to the NOTICE file at the top of the ITK source tree.
*
*=========================================================================*/
#ifndef itkShrinkImageFilter_hxx
#define itkShrinkImageFilter_hxx
#include "itkImageRegionIteratorWithIndex.h"
#include "itkContinuousIndex.h"
#include "itkObjectFactory.h"
#include "itkTotalProgressReporter.h"
namespace itk
{
template <typename TInputImage, typename TOutputImage>
ShrinkImageFilter<TInputImage, TOutputImage>::ShrinkImageFilter()
{
for (unsigned int j = 0; j < ImageDimension; ++j)
{
m_ShrinkFactors[j] = 1;
}
this->DynamicMultiThreadingOn();
this->ThreaderUpdateProgressOff();
}
template <typename TInputImage, typename TOutputImage>
void
ShrinkImageFilter<TInputImage, TOutputImage>::PrintSelf(std::ostream & os, Indent indent) const
{
Superclass::PrintSelf(os, indent);
os << indent << "Shrink Factor: ";
for (unsigned int j = 0; j < ImageDimension; ++j)
{
os << m_ShrinkFactors[j] << ' ';
}
os << std::endl;
}
template <typename TInputImage, typename TOutputImage>
void
ShrinkImageFilter<TInputImage, TOutputImage>::SetShrinkFactors(unsigned int factor)
{
unsigned int j;
for (j = 0; j < ImageDimension; ++j)
{
if (factor != m_ShrinkFactors[j])
{
break;
}
}
if (j < ImageDimension)
{
this->Modified();
for (j = 0; j < ImageDimension; ++j)
{
m_ShrinkFactors[j] = factor;
if (m_ShrinkFactors[j] < 1)
{
m_ShrinkFactors[j] = 1;
}
}
}
}
template <typename TInputImage, typename TOutputImage>
void
ShrinkImageFilter<TInputImage, TOutputImage>::SetShrinkFactor(unsigned int i, unsigned int factor)
{
if (m_ShrinkFactors[i] == factor)
{
return;
}
this->Modified();
m_ShrinkFactors[i] = factor;
}
template <typename TInputImage, typename TOutputImage>
void
ShrinkImageFilter<TInputImage, TOutputImage>::DynamicThreadedGenerateData(
const OutputImageRegionType & outputRegionForThread)
{
// Get the input and output pointers
InputImageConstPointer inputPtr = this->GetInput();
OutputImagePointer outputPtr = this->GetOutput();
TotalProgressReporter progress(this, outputPtr->GetRequestedRegion().GetNumberOfPixels());
// Convert the factor for convenient multiplication
unsigned int i;
typename TOutputImage::SizeType factorSize;
for (i = 0; i < TInputImage::ImageDimension; ++i)
{
factorSize[i] = m_ShrinkFactors[i];
}
// Define a few indices that will be used to transform from an input pixel
// to an output pixel
OutputIndexType outputIndex;
InputIndexType inputIndex;
OutputOffsetType offsetIndex;
typename TOutputImage::PointType tempPoint;
// Use this index to compute the offset everywhere in this class
outputIndex = outputPtr->GetLargestPossibleRegion().GetIndex();
// We wish to perform the following mapping of outputIndex to
// inputIndex on all points in our region
outputPtr->TransformIndexToPhysicalPoint(outputIndex, tempPoint);
inputIndex = inputPtr->TransformPhysicalPointToIndex(tempPoint);
// Given that the size is scaled by a constant factor eq:
// inputIndex = outputIndex * factorSize
// is equivalent up to a fixed offset which we now compute
OffsetValueType zeroOffset = 0;
for (i = 0; i < TInputImage::ImageDimension; ++i)
{
offsetIndex[i] = inputIndex[i] - outputIndex[i] * m_ShrinkFactors[i];
// It is plausible that due to small amounts of loss of numerical
// precision that the offset it negative, this would cause sampling
// out of out region, this is insurance against that possibility
offsetIndex[i] = std::max(zeroOffset, offsetIndex[i]);
}
// Define/declare an iterator that will walk the output region for this
// thread.
using OutputIterator = ImageRegionIteratorWithIndex<TOutputImage>;
for (OutputIterator outIt(outputPtr, outputRegionForThread); !outIt.IsAtEnd(); ++outIt)
{
// Determine the index and physical location of the output pixel
outputIndex = outIt.GetIndex();
// An optimized version of
// outputPtr->TransformIndexToPhysicalPoint(outputIndex, tempPoint);
// inputPtr->TransformPhysicalPointToIndex(tempPoint, inputIndex);
// but without the rounding and precision issues
inputIndex = outputIndex * factorSize + offsetIndex;
// Copy the input pixel to the output
outIt.Set(inputPtr->GetPixel(inputIndex));
progress.CompletedPixel();
}
}
template <typename TInputImage, typename TOutputImage>
void
ShrinkImageFilter<TInputImage, TOutputImage>::GenerateInputRequestedRegion()
{
// Call the superclass' implementation of this method
Superclass::GenerateInputRequestedRegion();
// Get pointers to the input and output
auto * inputPtr = const_cast<InputImageType *>(this->GetInput());
const OutputImageType * outputPtr = this->GetOutput();
itkAssertInDebugAndIgnoreInReleaseMacro(inputPtr != nullptr);
itkAssertInDebugAndIgnoreInReleaseMacro(outputPtr);
// Compute the input requested region (size and start index)
// Use the image transformations to insure an input requested region
// that will provide the proper range
unsigned int i;
const typename TOutputImage::SizeType & outputRequestedRegionSize = outputPtr->GetRequestedRegion().GetSize();
const typename TOutputImage::IndexType & outputRequestedRegionStartIndex = outputPtr->GetRequestedRegion().GetIndex();
// Convert the factor for convenient multiplication
typename TOutputImage::SizeType factorSize;
for (i = 0; i < TInputImage::ImageDimension; ++i)
{
factorSize[i] = m_ShrinkFactors[i];
}
OutputIndexType outputIndex;
InputIndexType inputIndex, inputRequestedRegionIndex;
OutputOffsetType offsetIndex;
typename TInputImage::SizeType inputRequestedRegionSize;
typename TOutputImage::PointType tempPoint;
// Use this index to compute the offset everywhere in this class
outputIndex = outputPtr->GetLargestPossibleRegion().GetIndex();
// We wish to perform the following mapping of outputIndex to
// inputIndex on all points in our region
outputPtr->TransformIndexToPhysicalPoint(outputIndex, tempPoint);
inputIndex = inputPtr->TransformPhysicalPointToIndex(tempPoint);
// Given that the size is scaled by a constant factor eq:
// inputIndex = outputIndex * factorSize
// is equivalent up to a fixed offset which we now compute
OffsetValueType zeroOffset = 0;
for (i = 0; i < TInputImage::ImageDimension; ++i)
{
offsetIndex[i] = inputIndex[i] - outputIndex[i] * m_ShrinkFactors[i];
// It is plausible that due to small amounts of loss of numerical
// precision that the offset it negative, this would cause sampling
// out of out region, this is insurance against that possibility
offsetIndex[i] = std::max(zeroOffset, offsetIndex[i]);
}
inputRequestedRegionIndex = outputRequestedRegionStartIndex * factorSize + offsetIndex;
// originally this was
// inputRequestedRegionSize = outputRequestedRegionSize * factorSize;
// but since we don't sample edge to edge, we can reduce the size
for (i = 0; i < TInputImage::ImageDimension; ++i)
{
inputRequestedRegionSize[i] = (outputRequestedRegionSize[i] - 1) * factorSize[i] + 1;
}
typename TInputImage::RegionType inputRequestedRegion;
inputRequestedRegion.SetIndex(inputRequestedRegionIndex);
inputRequestedRegion.SetSize(inputRequestedRegionSize);
inputRequestedRegion.Crop(inputPtr->GetLargestPossibleRegion());
inputPtr->SetRequestedRegion(inputRequestedRegion);
}
template <typename TInputImage, typename TOutputImage>
void
ShrinkImageFilter<TInputImage, TOutputImage>::GenerateOutputInformation()
{
// Call the superclass' implementation of this method
Superclass::GenerateOutputInformation();
// Get pointers to the input and output
const InputImageType * inputPtr = this->GetInput();
OutputImageType * outputPtr = this->GetOutput();
itkAssertInDebugAndIgnoreInReleaseMacro(inputPtr);
itkAssertInDebugAndIgnoreInReleaseMacro(outputPtr != nullptr);
// Compute the output spacing, the output image size, and the
// output image start index
unsigned int i;
const typename TInputImage::SpacingType & inputSpacing = inputPtr->GetSpacing();
const typename TInputImage::SizeType & inputSize = inputPtr->GetLargestPossibleRegion().GetSize();
const typename TInputImage::IndexType & inputStartIndex = inputPtr->GetLargestPossibleRegion().GetIndex();
typename TOutputImage::SpacingType outputSpacing;
typename TOutputImage::SizeType outputSize;
typename TOutputImage::IndexType outputStartIndex;
for (i = 0; i < TOutputImage::ImageDimension; ++i)
{
outputSpacing[i] = inputSpacing[i] * static_cast<double>(m_ShrinkFactors[i]);
// Round down so that all output pixels fit input input region
outputSize[i] = static_cast<SizeValueType>(
std::floor(static_cast<double>(inputSize[i]) / static_cast<double>(m_ShrinkFactors[i])));
if (outputSize[i] < 1)
{
outputSize[i] = 1;
}
// Because of the later origin shift this starting index is not
// critical
outputStartIndex[i] = static_cast<IndexValueType>(
std::ceil(static_cast<double>(inputStartIndex[i]) / static_cast<double>(m_ShrinkFactors[i])));
}
outputPtr->SetSpacing(outputSpacing);
// Compute origin offset
// The physical center's of the input and output should be the same
ContinuousIndex<SpacePrecisionType, TOutputImage::ImageDimension> inputCenterIndex;
ContinuousIndex<SpacePrecisionType, TOutputImage::ImageDimension> outputCenterIndex;
for (i = 0; i < TOutputImage::ImageDimension; ++i)
{
inputCenterIndex[i] = inputStartIndex[i] + (inputSize[i] - 1) / 2.0;
outputCenterIndex[i] = outputStartIndex[i] + (outputSize[i] - 1) / 2.0;
}
typename TOutputImage::PointType inputCenterPoint;
typename TOutputImage::PointType outputCenterPoint;
inputPtr->TransformContinuousIndexToPhysicalPoint(inputCenterIndex, inputCenterPoint);
outputPtr->TransformContinuousIndexToPhysicalPoint(outputCenterIndex, outputCenterPoint);
const typename TOutputImage::PointType & inputOrigin = inputPtr->GetOrigin();
typename TOutputImage::PointType outputOrigin;
outputOrigin = inputOrigin + (inputCenterPoint - outputCenterPoint);
outputPtr->SetOrigin(outputOrigin);
// Set region
const typename TOutputImage::RegionType outputLargestPossibleRegion(outputStartIndex, outputSize);
outputPtr->SetLargestPossibleRegion(outputLargestPossibleRegion);
}
} // end namespace itk
#endif
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