ITK  5.2.0
Insight Toolkit
Examples/IO/ImageReadCastWrite.cxx
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* Licensed under the Apache License, Version 2.0 (the "License");
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// Software Guide : BeginLatex
//
// Given that \href{https://www.itk.org}{ITK} is based on the Generic
// Programming paradigm, most of the types are defined at compilation
// time. It is sometimes important to anticipate conversion between different
// types of images. The following example illustrates the common case of
// reading an image of one pixel type and writing it as a different pixel
// type. This process not only involves casting but also rescaling the image
// intensity since the dynamic range of the input and output pixel types can
// be quite different. The \doxygen{RescaleIntensityImageFilter} is used
// here to linearly rescale the image values.
//
// The first step in this example is to include the appropriate headers.
//
// \index{itk::ImageFileReader!header}
// \index{itk::ImageFileWriter!header}
// \index{itk::RescaleIntensityImageFilter!header}
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
// Software Guide : EndCodeSnippet
#include "itkImage.h"
int
main(int argc, char ** argv)
{
// Verify the number of parameters in the command line
if (argc < 3)
{
std::cerr << "Usage: " << std::endl;
std::cerr << argv[0] << " inputImageFile outputImageFile " << std::endl;
return EXIT_FAILURE;
}
// Software Guide : BeginLatex
//
// Then, as usual, a decision should be made about the pixel type that
// should be used to represent the images. Note that when reading an
// image, this pixel type \textbf{is not necessarily} the pixel type of
// the image stored in the file. Instead, it is the type that will be
// used to store the image as soon as it is read into memory.
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
using InputPixelType = float;
using OutputPixelType = unsigned char;
constexpr unsigned int Dimension = 2;
using InputImageType = itk::Image<InputPixelType, Dimension>;
using OutputImageType = itk::Image<OutputPixelType, Dimension>;
// Software Guide : EndCodeSnippet
// Software Guide : BeginLatex
//
// Note that the dimension of the image in memory should match the one of
// the image in the file. There are a couple of special cases in which this
// condition may be relaxed, but in general it is better to ensure that
// both dimensions match.
//
// We can now instantiate the types of the reader and writer. These two
// classes are parameterized over the image type.
//
// \index{itk::ImageFileReader!Instantiation}
// \index{itk::ImageFileWriter!Instantiation}
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
// Software Guide : EndCodeSnippet
// Software Guide : BeginLatex
//
// Below we instantiate the RescaleIntensityImageFilter class that will
// linearly scale the image intensities.
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
using FilterType =
// Software Guide : EndCodeSnippet
// Software Guide : BeginLatex
//
// A filter object is constructed and the minimum and maximum values of
// the output are selected using the \code{SetOutputMinimum()} and
// \code{SetOutputMaximum()} methods.
//
// \index{itk::RescaleIntensityImageFilter!SetOutputMinimum()}
// \index{itk::RescaleIntensityImageFilter!SetOutputMaximum()}
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
FilterType::Pointer filter = FilterType::New();
filter->SetOutputMinimum(0);
filter->SetOutputMaximum(255);
// Software Guide : EndCodeSnippet
// Software Guide : BeginLatex
//
// Then, we create the reader and writer and connect the pipeline.
//
// \index{itk::ImageFileReader!New()}
// \index{itk::ImageFileWriter!New()}
// \index{itk::ImageFileReader!SmartPointer}
// \index{itk::ImageFileWriter!SmartPointer}
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
ReaderType::Pointer reader = ReaderType::New();
WriterType::Pointer writer = WriterType::New();
filter->SetInput(reader->GetOutput());
writer->SetInput(filter->GetOutput());
// Software Guide : EndCodeSnippet
//
// Here we recover the file names from the command line arguments
//
const char * inputFilename = argv[1];
const char * outputFilename = argv[2];
// Software Guide : BeginLatex
//
// The name of the files to be read and written are passed with the
// \code{SetFileName()} method.
//
// \index{itk::ImageFileReader!SetFileName()}
// \index{itk::ImageFileWriter!SetFileName()}
// \index{SetFileName()!itk::ImageFileReader}
// \index{SetFileName()!itk::ImageFileWriter}
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
reader->SetFileName(inputFilename);
writer->SetFileName(outputFilename);
// Software Guide : EndCodeSnippet
// Software Guide : BeginLatex
//
// Finally we trigger the execution of the pipeline with the
// \code{Update()} method on the writer. The output image will then be the
// scaled and cast version of the input image.
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
try
{
writer->Update();
}
catch (const itk::ExceptionObject & err)
{
std::cerr << "ExceptionObject caught !" << std::endl;
std::cerr << err << std::endl;
return EXIT_FAILURE;
}
// Software Guide : EndCodeSnippet
return EXIT_SUCCESS;
}
itkImageFileReader.h
itkImage.h
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