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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 "itkMath.h"
#include "itkSigmoidImageFilter.h"
#include "itkTestingMacros.h"
int
itkSigmoidImageFilterTest(int, char *[])
{
// Define the dimension of the images
constexpr unsigned int ImageDimension = 3;
// Declare the types of the images
using InputPixelType = float;
using OutputPixelType = float;
using InputImageType = itk::Image<InputPixelType, ImageDimension>;
using OutputImageType = itk::Image<OutputPixelType, ImageDimension>;
// Declare appropriate Iterator types for each image
using InputIteratorType = itk::ImageRegionIteratorWithIndex<InputImageType>;
using OutputIteratorType = itk::ImageRegionIteratorWithIndex<OutputImageType>;
// Declare the type of the index to access images
using IndexType = itk::Index<ImageDimension>;
// Declare the type of the size
using SizeType = itk::Size<ImageDimension>;
// Declare the type of the Region
using RegionType = itk::ImageRegion<ImageDimension>;
// Create the input images
auto inputImage = InputImageType::New();
// Define their size, and start index
SizeType size;
size[0] = 2;
size[1] = 2;
size[2] = 2;
IndexType start;
start[0] = 0;
start[1] = 0;
start[2] = 0;
RegionType region;
region.SetIndex(start);
region.SetSize(size);
// Initialize the input image
inputImage->SetRegions(region);
inputImage->Allocate();
// Create one iterator for the input image (this is a light object)
InputIteratorType it(inputImage, inputImage->GetBufferedRegion());
// Initialize the content of the input image
constexpr double value = 30;
it.GoToBegin();
while (!it.IsAtEnd())
{
it.Set(value);
++it;
}
// Declare the type for the Sigmoid filter
using FilterType = itk::SigmoidImageFilter<InputImageType, OutputImageType>;
// Create the filter
auto filter = FilterType::New();
ITK_EXERCISE_BASIC_OBJECT_METHODS(filter, SigmoidImageFilter, UnaryFunctorImageFilter);
// Set the input image
filter->SetInput(inputImage);
// Set the filter parameters
constexpr double alpha = 2.0;
constexpr double beta = 3.0;
filter->SetAlpha(alpha);
ITK_TEST_SET_GET_VALUE(alpha, filter->GetAlpha());
filter->SetBeta(beta);
ITK_TEST_SET_GET_VALUE(beta, filter->GetBeta());
constexpr OutputPixelType maximum = 1.0;
const OutputPixelType minimum = -1.0;
filter->SetOutputMinimum(minimum);
ITK_TEST_SET_GET_VALUE(minimum, filter->GetOutputMinimum());
filter->SetOutputMaximum(maximum);
ITK_TEST_SET_GET_VALUE(maximum, filter->GetOutputMaximum());
filter->SetFunctor(filter->GetFunctor());
// Execute the filter
filter->Update();
// Get the filter output
OutputImageType::Pointer outputImage = filter->GetOutput();
// Create an iterator for going through the image output
OutputIteratorType ot(outputImage, outputImage->GetRequestedRegion());
// Check the content of the result image
const OutputImageType::PixelType epsilon = 1e-6;
ot.GoToBegin();
it.GoToBegin();
while (!ot.IsAtEnd())
{
const InputImageType::PixelType input = it.Get();
const OutputImageType::PixelType output = ot.Get();
const double x1 = (input - beta) / alpha;
const double x2 = (maximum - minimum) * (1.0 / (1.0 + std::exp(-x1))) + minimum;
const auto sigmoid = static_cast<OutputImageType::PixelType>(x2);
if (!itk::Math::FloatAlmostEqual(sigmoid, output, 10, epsilon))
{
std::cerr.precision(static_cast<int>(itk::Math::abs(std::log10(epsilon))));
std::cerr << "Error " << std::endl;
std::cerr << " simoid( " << input << ") = " << sigmoid << std::endl;
std::cerr << " differs from " << output;
std::cerr << " by more than " << epsilon << std::endl;
return EXIT_FAILURE;
}
++ot;
++it;
}
return EXIT_SUCCESS;
}
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