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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.
*
*=========================================================================*/
// First include the header file to be tested:
#include "itkGradientImageFilter.h"
#include "itkDeref.h"
#include "itkImage.h"
#include "itkImageBufferRange.h"
#include "itkIndexRange.h"
#include <gtest/gtest.h>
// Tests the output for a uniform input image.
TEST(GradientImageFilter, UniformInputImage)
{
static constexpr unsigned int Dimension{ 3 };
using PixelType = int;
using ImageType = itk::Image<PixelType, Dimension>;
using ImageSizeType = itk::Size<Dimension>;
using FilterType = itk::GradientImageFilter<ImageType>;
for (const PixelType inputPixelValue :
{ std::numeric_limits<PixelType>::lowest(), PixelType{ 1 }, std::numeric_limits<PixelType>::max() })
{
const auto filter = FilterType::New();
// Keep the image size small, in order to keep the unit test fast!
static constexpr auto imageSize = ImageSizeType::Filled(4);
const auto inputImage = ImageType::New();
inputImage->SetRegions(imageSize);
inputImage->Allocate(false);
inputImage->FillBuffer(inputPixelValue);
filter->SetInput(inputImage);
filter->Update();
const auto & output = itk::Deref(filter->GetOutput());
const itk::ImageBufferRange outputImageBufferRange(output);
EXPECT_EQ(outputImageBufferRange.size(), imageSize.CalculateProductOfElements());
for (const auto & outputValue : outputImageBufferRange)
{
// Expect all output pixels to be zero.
EXPECT_EQ(outputValue, FilterType::OutputPixelType{});
}
}
}
// Tests the output for an input image that has a constant gradient along its first dimension.
TEST(GradientImageFilter, ConstantGradientInputImage)
{
static constexpr unsigned int Dimension{ 3 };
using PixelType = int;
using ImageType = itk::Image<PixelType, Dimension>;
using IndexType = itk::Index<Dimension>;
using SizeType = itk::Size<Dimension>;
using FilterType = itk::GradientImageFilter<ImageType>;
using OutputValueType = FilterType::OutputValueType;
for (int inputGradientValue{ -1 }; inputGradientValue <= 2; ++inputGradientValue)
{
const auto filter = FilterType::New();
// Keep the image size small, in order to keep the unit test fast!
static constexpr auto imageSize = SizeType::Filled(4);
const auto inputImage = ImageType::New();
inputImage->SetRegions(imageSize);
inputImage->Allocate(false);
for (const auto & index : itk::ZeroBasedIndexRange<Dimension>(imageSize))
{
// A constant gradient along the first dimension of the image.
inputImage->SetPixel(index, static_cast<PixelType>(inputGradientValue * index[0]));
}
filter->SetInput(inputImage);
filter->Update();
const auto & output = itk::Deref(filter->GetOutput());
ASSERT_EQ(output.GetBufferedRegion().GetSize(), imageSize);
// Only look at the inner region, to avoid boundary effects (which are beyond the scope of this unit test).
const itk::ImageRegion innerRegion{ IndexType::Filled(1), imageSize - SizeType::Filled(2) };
for (const auto & index : itk::ImageRegionIndexRange<Dimension>(innerRegion))
{
const auto outputPixelValue = output.GetPixel(index);
EXPECT_EQ(outputPixelValue[0], inputGradientValue);
for (unsigned int i{ 1 }; i < Dimension; ++i)
{
EXPECT_EQ(outputPixelValue[i], OutputValueType{ 0 });
}
}
}
}
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