ITK  5.2.0
Insight Toolkit
Examples/Filtering/DerivativeImageFilter.cxx
/*=========================================================================
*
* 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
*
* http://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.
*
*=========================================================================*/
// Software Guide : BeginCommandLineArgs
// INPUTS: {BrainProtonDensitySlice.png}
// ARGUMENTS: {DerivativeImageFilterFloatOutput.mhd}
// OUTPUTS: {DerivativeImageFilterOutput.png}
// ARGUMENTS: 1 0
// Software Guide : EndCommandLineArgs
// Software Guide : BeginLatex
//
// The \doxygen{DerivativeImageFilter} is used for computing the partial
// derivative of an image, the derivative of an image along a particular
// axial direction.
//
// \index{itk::DerivativeImageFilter}
//
// Software Guide : EndLatex
#include "itkImage.h"
// Software Guide : BeginLatex
//
// The header file corresponding to this filter should be included first.
//
// \index{itk::DerivativeImageFilter!header}
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
// Software Guide : EndCodeSnippet
int
main(int argc, char * argv[])
{
if (argc < 6)
{
std::cerr << "Usage: " << std::endl;
std::cerr
<< argv[0]
<< " inputImageFile outputImageFile normalizedOutputImageFile ";
std::cerr << " derivativeOrder direction" << std::endl;
return EXIT_FAILURE;
}
// Software Guide : BeginLatex
//
// Next, the pixel types for the input and output images must be defined
// and, with them, the image types can be instantiated. Note that it is
// important to select a signed type for the image, since the values of the
// derivatives will be positive as well as negative.
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
using InputPixelType = float;
using OutputPixelType = float;
constexpr unsigned int Dimension = 2;
using InputImageType = itk::Image<InputPixelType, Dimension>;
using OutputImageType = itk::Image<OutputPixelType, Dimension>;
// Software Guide : EndCodeSnippet
ReaderType::Pointer reader = ReaderType::New();
WriterType::Pointer writer = WriterType::New();
reader->SetFileName(argv[1]);
writer->SetFileName(argv[2]);
// Software Guide : BeginLatex
//
// Using the image types, it is now possible to define the filter type
// and create the filter object.
//
// \index{itk::DerivativeImageFilter!instantiation}
// \index{itk::DerivativeImageFilter!New()}
// \index{itk::DerivativeImageFilter!Pointer}
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
using FilterType =
FilterType::Pointer filter = FilterType::New();
// Software Guide : EndCodeSnippet
// Software Guide : BeginLatex
//
// The order of the derivative is selected with the \code{SetOrder()}
// method. The direction along which the derivative will be computed is
// selected with the \code{SetDirection()} method.
//
// \index{itk::DerivativeImageFilter!SetOrder()}
// \index{itk::DerivativeImageFilter!SetDirection()}
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
filter->SetOrder(std::stoi(argv[4]));
filter->SetDirection(std::stoi(argv[5]));
// Software Guide : EndCodeSnippet
// Software Guide : BeginLatex
//
// The input to the filter can be taken from any other filter, for example
// a reader. The output can be passed down the pipeline to other filters,
// for example, a writer. An \code{Update()} call on any downstream filter
// will trigger the execution of the derivative filter.
//
// \index{itk::DerivativeImageFilter!SetInput()}
// \index{itk::DerivativeImageFilter!GetOutput()}
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
filter->SetInput(reader->GetOutput());
writer->SetInput(filter->GetOutput());
writer->Update();
// Software Guide : EndCodeSnippet
// Software Guide : BeginLatex
//
// \begin{figure}
// \center
// \includegraphics[width=0.44\textwidth]{BrainProtonDensitySlice}
// \includegraphics[width=0.44\textwidth]{DerivativeImageFilterOutput}
// \itkcaption[Effect of the Derivative filter.]{Effect of the Derivative
// filter on a slice from a MRI proton density brain image.}
// \label{fig:DerivativeImageFilterOutput}
// \end{figure}
//
// Figure \ref{fig:DerivativeImageFilterOutput} illustrates the effect of
// the DerivativeImageFilter on a slice of MRI brain image. The derivative
// is taken along the $x$ direction. The sensitivity to noise in the image
// is evident from this result.
//
// Software Guide : EndLatex
using WriteImageType = itk::Image<unsigned char, Dimension>;
using NormalizeFilterType =
using NormalizedWriterType = itk::ImageFileWriter<WriteImageType>;
NormalizeFilterType::Pointer normalizer = NormalizeFilterType::New();
NormalizedWriterType::Pointer normalizedWriter =
NormalizedWriterType::New();
normalizer->SetInput(filter->GetOutput());
normalizedWriter->SetInput(normalizer->GetOutput());
normalizer->SetOutputMinimum(0);
normalizer->SetOutputMaximum(255);
normalizedWriter->SetFileName(argv[3]);
normalizedWriter->Update();
return EXIT_SUCCESS;
}
itkImageFileReader.h
itkImage.h
itk::DerivativeImageFilter
Computes the directional derivative of an image. The directional derivative at each pixel location is...
Definition: itkDerivativeImageFilter.h:50
itk::ImageFileReader
Data source that reads image data from a single file.
Definition: itkImageFileReader.h:75
itk::ImageFileWriter
Writes image data to a single file.
Definition: itkImageFileWriter.h:87
itkRescaleIntensityImageFilter.h
itkImageFileWriter.h
itk::RescaleIntensityImageFilter
Applies a linear transformation to the intensity levels of the input Image.
Definition: itkRescaleIntensityImageFilter.h:154
itk::Image
Templated n-dimensional image class.
Definition: itkImage.h:86
itk::GTest::TypedefsAndConstructors::Dimension2::Dimension
constexpr unsigned int Dimension
Definition: itkGTestTypedefsAndConstructors.h:44
itkDerivativeImageFilter.h