ITK  5.2.0
Insight Toolkit
Examples/DataRepresentation/Image/ImageAdaptor2.cxx
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* Copyright NumFOCUS
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* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
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// Software Guide : BeginLatex
//
// This example illustrates how to use the \doxygen{ImageAdaptor}
// to access the individual components of an RGB image. In this case, we
// create an ImageAdaptor that will accept a RGB image as input and
// presents it as a scalar image. The pixel data
// will be taken directly from the red channel of the original image.
//
// \index{itk::ImageAdaptor!Instantiation}
// \index{itk::ImageAdaptor!Header}
//
// Software Guide : EndLatex
// Software Guide : BeginLatex
//
// As with the previous example, the bulk of the effort in creating the image
// adaptor is associated with the definition of the pixel accessor class. In
// this case, the accessor converts a RGB vector to a scalar containing the
// red channel component. Note that in the following, we do not need to
// define the \code{Set()} method since we only expect the adaptor to be used
// for reading data from the image.
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
class RedChannelPixelAccessor
{
public:
using InternalType = itk::RGBPixel<float>;
using ExternalType = float;
static ExternalType
Get(const InternalType & input)
{
return static_cast<ExternalType>(input.GetRed());
}
};
// Software Guide : EndCodeSnippet
// Software Guide : BeginLatex
//
// The \code{Get()} method simply calls the \code{GetRed()} method
// defined in the \doxygen{RGBPixel} class.
//
// Software Guide : EndLatex
//-------------------------
//
// Main code
//
//-------------------------
int
main(int argc, char * argv[])
{
if (argc < 3)
{
std::cerr << "Usage: " << std::endl;
std::cerr << "ImageAdaptor2 inputRGBFileName outputRedChannelFileName"
<< std::endl;
return EXIT_FAILURE;
}
// Software Guide : BeginLatex
//
// Now we use the internal pixel type of the pixel accessor to define the
// input image type, and then proceed to instantiate the ImageAdaptor type.
//
// \index{PixelAccessor!RGB red channel}
// \index{itk::ImageAdaptor!RGB red channel}
// \index{ImageAdaptor!RGB red channel}
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
using InputPixelType = RedChannelPixelAccessor::InternalType;
constexpr unsigned int Dimension = 2;
using ImageAdaptorType =
ImageAdaptorType::Pointer adaptor = ImageAdaptorType::New();
// Software Guide : EndCodeSnippet
// Software Guide : BeginLatex
//
// We create an image reader and connect the output to the adaptor
// as before.
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
using ReaderType = itk::ImageFileReader<ImageType>;
ReaderType::Pointer reader = ReaderType::New();
// Software Guide : EndCodeSnippet
reader->SetFileName(argv[1]);
reader->Update();
// Software Guide : BeginCodeSnippet
adaptor->SetImage(reader->GetOutput());
// Software Guide : EndCodeSnippet
// Software Guide : BeginLatex
//
// We create an \doxygen{RescaleIntensityImageFilter} and an
// \doxygen{ImageFileWriter} to rescale the dynamic range of the pixel
// values and send the extracted channel to an image file. Note that the
// image type used for the rescaling filter is the \code{ImageAdaptorType}
// itself. That is, the adaptor type is used in the same context as an
// image type.
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
using OutputImageType = itk::Image<unsigned char, Dimension>;
using RescalerType =
RescalerType::Pointer rescaler = RescalerType::New();
WriterType::Pointer writer = WriterType::New();
// Software Guide : EndCodeSnippet
writer->SetFileName(argv[2]);
// Software Guide : BeginLatex
//
// Now we connect the adaptor as the input to the rescaler and set the
// parameters for the intensity rescaling.
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
rescaler->SetOutputMinimum(0);
rescaler->SetOutputMaximum(255);
rescaler->SetInput(adaptor);
writer->SetInput(rescaler->GetOutput());
// Software Guide : EndCodeSnippet
// Software Guide : BeginLatex
//
// Finally, we invoke the \code{Update()} method on the writer and take
// precautions to catch any exception that may be thrown during
// the execution of the pipeline.
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
try
{
writer->Update();
}
catch (const itk::ExceptionObject & excp)
{
std::cerr << "Exception caught " << excp << std::endl;
return EXIT_FAILURE;
}
// Software Guide : EndCodeSnippet
// Software Guide : BeginLatex
//
// ImageAdaptors for the green and blue channels can easily be implemented
// by modifying the pixel accessor of the red channel and then using the
// new pixel accessor for instantiating the type of an image adaptor.
// The following define a green channel pixel accessor.
//
// \index{PixelAccessor!RGB green channel}
// \index{itk::ImageAdaptor!RGB green channel}
// \index{ImageAdaptor!RGB green channel}
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
class GreenChannelPixelAccessor
{
public:
using InternalType = itk::RGBPixel<float>;
using ExternalType = float;
static ExternalType
Get(const InternalType & input)
{
return static_cast<ExternalType>(input.GetGreen());
}
};
// Software Guide : EndCodeSnippet
// Software Guide : BeginLatex
//
// A blue channel pixel accessor is similarly defined.
//
// \index{PixelAccessor!RGB blue channel}
// \index{itk::ImageAdaptor!RGB blue channel}
// \index{ImageAdaptor!RGB blue channel}
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
class BlueChannelPixelAccessor
{
public:
using InternalType = itk::RGBPixel<float>;
using ExternalType = float;
static ExternalType
Get(const InternalType & input)
{
return static_cast<ExternalType>(input.GetBlue());
}
};
// Software Guide : EndCodeSnippet
// Software Guide : BeginLatex
//
// \begin{figure} \center
// \includegraphics[width=0.24\textwidth]{VisibleWomanEyeSlice}
// \includegraphics[width=0.24\textwidth]{VisibleWomanEyeSliceRedComponent}
// \includegraphics[width=0.24\textwidth]{VisibleWomanEyeSliceGreenComponent}
// \includegraphics[width=0.24\textwidth]{VisibleWomanEyeSliceBlueComponent}
// \itkcaption[Image Adaptor to RGB Image]{Using
// ImageAdaptor to extract the components of an RGB image. The
// image on the left is a subregion of the Visible Woman cryogenic data set.
// The red, green and blue components are shown from left to right as scalar
// images extracted with an ImageAdaptor.}
// \label{fig:ImageAdaptorToRGBImage}
// \end{figure}
//
//
// Figure~\ref{fig:ImageAdaptorToRGBImage} shows the result
// of extracting the red, green and blue components from a region of the
// Visible Woman cryogenic data set.
//
// Software Guide : EndLatex
return EXIT_SUCCESS;
}
itk::RGBPixel
Represent Red, Green and Blue components for color images.
Definition: itkRGBPixel.h:58
itkImageFileReader.h
itkImageAdaptor.h
itkImageRegionIteratorWithIndex.h
itk::ImageAdaptor
Give access to partial aspects of voxels from an Image.
Definition: itkImageAdaptor.h:56
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