ITK  5.2.0
Insight Toolkit
Examples/IO/ImageReadExportVTK.cxx
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* Copyright NumFOCUS
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* Licensed under the Apache License, Version 2.0 (the "License");
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* You may obtain a copy of the License at
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// Software Guide : BeginLatex
//
// In cases where the user knows what file format to use and wants to
// indicate this explicitly, a specific \doxygen{ImageIO} class can be
// instantiated and assigned to the image file reader or writer. This
// circumvents the \doxygen{ImageIOFactory} mechanism which tries to find
// the appropriate ImageIO class for performing the IO operations. Explicit
// selection of the ImageIO also allows the user to invoke specialized
// features of a particular class which may not be available from the
// general API provided by ImageIO.
//
// The following example illustrates explicit instantiation of an IO class
// (in this case a VTK file format), setting its parameters and then
// connecting it to the \doxygen{ImageFileWriter}.
//
// The example begins by including the appropriate headers.
//
// \index{itk::ImageFileReader!header}
// \index{itk::ImageFileWriter!header}
// \index{itk::VTKImageIO!header}
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
#include "itkVTKImageIO.h"
// 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, we select the pixel types and the image
// dimension. Remember, if the file format represents pixels with a
// particular type, C-style casting will be performed to convert the data.
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
using PixelType = unsigned short;
constexpr unsigned int Dimension = 2;
// Software Guide : EndCodeSnippet
// Software Guide : BeginLatex
//
// We can now instantiate the reader and writer. These two classes are
// parameterized over the image type. We instantiate the
// \doxygen{VTKImageIO} class as well. Note that the ImageIO objects are
// not templated.
//
// \index{itk::ImageFileReader!Instantiation}
// \index{itk::ImageFileWriter!Instantiation}
// \index{itk::VTKImageIO!Instantiation}
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
using ReaderType = itk::ImageFileReader<ImageType>;
using WriterType = itk::ImageFileWriter<ImageType>;
using ImageIOType = itk::VTKImageIO;
// Software Guide : EndCodeSnippet
// Software Guide : BeginLatex
//
// Then, we create one object of each type using the New() method and
// assigning the result to a \doxygen{SmartPointer}.
//
// \index{itk::ImageFileReader!New()}
// \index{itk::ImageFileWriter!New()}
// \index{itk::ImageFileReader!SmartPointer}
// \index{itk::ImageFileWriter!SmartPointer}
// \index{itk::VTKImageIO!New()}
// \index{itk::VTKImageIO!SmartPointer}
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
ReaderType::Pointer reader = ReaderType::New();
WriterType::Pointer writer = WriterType::New();
ImageIOType::Pointer vtkIO = ImageIOType::New();
// 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 file to be read or written is passed with the
// SetFileName() method.
//
// \index{itk::ImageFileReader!SetFileName()}
// \index{itk::ImageFileWriter!SetFileName()}
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
reader->SetFileName(inputFilename);
writer->SetFileName(outputFilename);
// Software Guide : EndCodeSnippet
// Software Guide : BeginLatex
//
// We can now connect these readers and writers to filters in a
// pipeline. For example, we can create a short pipeline by passing the
// output of the reader directly to the input of the writer.
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
writer->SetInput(reader->GetOutput());
// Software Guide : EndCodeSnippet
// Software Guide : BeginLatex
//
// Explicitly declaring the specific VTKImageIO allow users to
// invoke methods specific to a particular IO class. For example, the
// following line specifies to the writer to use ASCII format when writing
// the pixel data.
//
// \index{itk::VTKImageIO!SetFileTypeToASCII()}
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
vtkIO->SetFileTypeToASCII();
// Software Guide : EndCodeSnippet
// Software Guide : BeginLatex
//
// The VTKImageIO object is then connected to the
// ImageFileWriter. This will short-circuit the action of the
// ImageIOFactory mechanism. The ImageFileWriter will
// not attempt to look for other ImageIO objects capable of
// performing the writing tasks. It will simply invoke the one provided by
// the user.
//
// \index{itk::ImageFileWriter!SetImageIO()}
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
writer->SetImageIO(vtkIO);
// Software Guide : EndCodeSnippet
// Software Guide : BeginLatex
//
// Finally we invoke Update() on the ImageFileWriter and
// place this call inside a try/catch block in case any errors occur during
// the writing process.
//
// \index{itk::ImageFileWriter!SetImageIO()}
//
// 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
// Software Guide : BeginLatex
//
// Although this example only illustrates how to use an explicit
// ImageIO class with the ImageFileWriter, the same
// can be done with the ImageFileReader. The typical case in
// which this is done is when reading raw image files with the
// \doxygen{RawImageIO} object. The drawback of this approach is that the
// parameters of the image have to be explicitly written in the code. The
// direct use of raw files is \textbf{strongly discouraged} in medical
// imaging. It is always better to create a header for a raw file by
// using any of the file formats that combine a text header file and a raw
// binary file, like \doxygen{MetaImageIO}, \doxygen{GiplImageIO} and
// \doxygen{VTKImageIO}.
//
// Software Guide : EndLatex
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
itkVTKImageIO.h
itkImageFileWriter.h
itk::VTKImageIO
ImageIO class for reading VTK images.
Definition: itkVTKImageIO.h:50
itk::Image
Templated n-dimensional image class.
Definition: itkImage.h:86
itk::GTest::TypedefsAndConstructors::Dimension2::Dimension
constexpr unsigned int Dimension
Definition: itkGTestTypedefsAndConstructors.h:44