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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.
*
*=========================================================================*/
#include "itkConstNeighborhoodIterator.h"
#include "itkImageFileReader.h"
#include "itkImageFileWriter.h"
#include "itkImageRegionIterator.h"
#include "itkNeighborhoodInnerProduct.h"
#include "itkSobelOperator.h"
#include "itkTestingMacros.h"
#include "itkRescaleIntensityImageFilter.h"
template <typename ImageType>
typename ImageType::Pointer
MakeOnes3x3Image()
{
typename ImageType::Pointer onesImage = ImageType::New();
{
typename ImageType::SizeType smallest_size{ { 3, 3 } };
typename ImageType::IndexType start_index{ { 0, 0 } };
typename ImageType::RegionType my_region(start_index, smallest_size);
onesImage->SetRegions(my_region);
}
onesImage->Allocate();
onesImage->FillBuffer(1);
return onesImage;
}
template <typename ImageType>
typename ImageType::Pointer
DoConvolution(typename ImageType::Pointer inputImage, unsigned long int direction)
{
using PixelType = typename ImageType::PixelType;
constexpr std::size_t Dimension = ImageType::ImageDimension;
using SobelOperatorType = itk::SobelOperator<PixelType, Dimension>;
using NeighborhoodIteratorType = itk::ConstNeighborhoodIterator<ImageType>;
using IteratorType = itk::ImageRegionIterator<ImageType>;
SobelOperatorType sobelOperator;
sobelOperator.SetDirection(direction);
itk::Size<Dimension> radius;
radius.Fill(1);
sobelOperator.CreateToRadius(radius);
NeighborhoodIteratorType it(radius, inputImage, inputImage->GetRequestedRegion());
auto outputImage = ImageType::New();
outputImage->SetRegions(inputImage->GetRequestedRegion());
outputImage->AllocateInitialized();
IteratorType out(outputImage, inputImage->GetRequestedRegion());
itk::NeighborhoodInnerProduct<ImageType> innerProduct;
for (it.GoToBegin(), out.GoToBegin(); !it.IsAtEnd(); ++it, ++out)
{
const auto pixelValue = innerProduct(it, sobelOperator);
out.Set(pixelValue);
}
return outputImage;
}
template <typename PixelType, unsigned long Dimension>
int
DoSimpleConvolutionTest(unsigned long direction, const std::string & pixelType)
{
using ImageType = typename itk::Image<PixelType, Dimension>;
typename ImageType::Pointer smallestOnesImage = MakeOnes3x3Image<ImageType>();
typename ImageType::Pointer output3x3Image = DoConvolution<ImageType>(smallestOnesImage, direction);
typename ImageType::IndexType center_index{ { 1, 1 } };
typename ImageType::PixelType center_value = output3x3Image->GetPixel(center_index);
if (center_value != 0)
{
std::cout << "ERROR: Constant image convolution with SobelOperator should return 0, "
<< "but value of " << +center_value << " was computed. [" << pixelType << "]" << std::endl;
return EXIT_FAILURE;
}
return EXIT_SUCCESS;
}
int
itkSobelOperatorImageConvolutionTest(int argc, char * argv[])
{
if (argc != 4)
{
std::cerr << "Missing parameters." << std::endl;
std::cerr << "Usage: " << itkNameOfTestExecutableMacro(argv) << " inputFileName direction outputFileName"
<< std::endl;
return EXIT_FAILURE;
}
const auto direction = std::stoul(argv[2]);
int return_status = EXIT_SUCCESS;
constexpr unsigned int Dimension = 2;
/* Sanity Checking For Sobel Operator */
//{
/*
* Demonstrate that signed types do **NOT** work with SobelOperator
* The unsigned checks require disableing Signed ConceptChecking in SobelOperator
* added in March 2023.
*/
/*
return_status += DoSimpleConvolutionTest<unsigned char, 2>(direction, "unsigned char");
return_status += DoSimpleConvolutionTest<unsigned short, 2>(direction, "unsigned short");
return_status += DoSimpleConvolutionTest<unsigned int, 2>(direction, "unsigned int");
return_status += DoSimpleConvolutionTest<unsigned long, 2>(direction, "unsigned long");
*/
//}
{
/*
* Demonstrate that signed types do work with SobelOperator
*/
// Note: `char` can be unsigned on some platforms.
return_status += DoSimpleConvolutionTest<signed char, 2>(direction, "signed char");
return_status += DoSimpleConvolutionTest<short, 2>(direction, "short");
return_status += DoSimpleConvolutionTest<int, 2>(direction, "int");
return_status += DoSimpleConvolutionTest<long, 2>(direction, "long");
return_status += DoSimpleConvolutionTest<float, 2>(direction, "float");
return_status += DoSimpleConvolutionTest<double, 2>(direction, "double");
}
{
/* Test on a real image */
using PixelType = int16_t;
using ImageType = itk::Image<PixelType, Dimension>;
const auto inputImage = itk::ReadImage<ImageType>(argv[1]);
auto signedSobelImage = DoConvolution<ImageType>(inputImage, direction);
using OutputImageType = itk::Image<uint8_t, Dimension>;
// Assume min/max values are approximately +/- same magnitude so that the output images
// to be stored in uint8_t have an implied 0 at about pixel value 128. Many web based viewers
// for the difference images in the testing outputs render better in this positive png range.
using RescaleIntensityType = itk::RescaleIntensityImageFilter<ImageType, OutputImageType>;
RescaleIntensityType::Pointer rescalerForVisualization = RescaleIntensityType::New();
rescalerForVisualization->SetInput(signedSobelImage);
rescalerForVisualization->SetOutputMinimum(0);
rescalerForVisualization->SetOutputMaximum(255);
rescalerForVisualization->Update();
itk::WriteImage(rescalerForVisualization->GetOutput(), argv[3]);
}
std::cout << "Test finished." << std::endl;
return return_status;
}
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