VectorImageReadWrite.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
 *
 *         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.
 *
 *=========================================================================*/

//  Software Guide : BeginLatex
//
//  This example illustrates how to read and write an image of pixel type
//  \itkref{Vector}.
//
//  \index{itk::ImageFileRead!Vector images}
//  \index{itk::ImageFileWrite!Vector images}
//  \index{Vector images!Reading}
//  \index{Vector images!Writing}
//
//  Software Guide : EndLatex

// Software Guide : BeginLatex
//
// We should include the header files for the Image, the ImageFileReader and
// the ImageFileWriter.
//
// Software Guide : EndLatex

// Software Guide : BeginCodeSnippet
#include "itkImage.h"
#include "itkImageFileReader.h"
#include "itkImageFileWriter.h"
// Software Guide : EndCodeSnippet


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 we define the specific type of vector to be used as pixel type.
  //
  // Software Guide : EndLatex

  // Software Guide : BeginCodeSnippet
  constexpr unsigned int VectorDimension = 3;

  using PixelType = itk::Vector<float, VectorDimension>;
  // Software Guide : EndCodeSnippet


  // Software Guide : BeginLatex
  //
  // We define the image dimension, and along with the pixel type we use it
  // for fully instantiating the image type.
  //
  // Software Guide : EndLatex

  // Software Guide : BeginCodeSnippet
  constexpr unsigned int ImageDimension = 2;

  using ImageType = itk::Image<PixelType, ImageDimension>;
  // Software Guide : EndCodeSnippet

  // Software Guide : BeginLatex
  //
  // Having the image type at hand, we can instantiate the reader and writer
  // types, and use them for creating one object of each type.
  //
  // Software Guide : EndLatex

  // Software Guide : BeginCodeSnippet
  using ReaderType = itk::ImageFileReader<ImageType>;
  using WriterType = itk::ImageFileWriter<ImageType>;

  auto reader = ReaderType::New();
  auto writer = WriterType::New();
  // Software Guide : EndCodeSnippet


  // Software Guide : BeginLatex
  //
  // A filename must be provided to both the reader and the writer. In this
  // particular case we take those filenames from the command line arguments.
  //
  // Software Guide : EndLatex

  // Software Guide : BeginCodeSnippet
  reader->SetFileName(argv[1]);
  writer->SetFileName(argv[2]);
  // Software Guide : EndCodeSnippet


  // Software Guide : BeginLatex
  //
  // This being a minimal example, we create a short pipeline where we simply
  // connect the output of the reader to the input of the writer.
  //
  // Software Guide : EndLatex

  // Software Guide : BeginCodeSnippet
  writer->SetInput(reader->GetOutput());
  // Software Guide : EndCodeSnippet

  // Software Guide : BeginLatex
  //
  // The execution of this short pipeline is triggered by invoking the
  // writer's \code{Update()} method. This invocation must be placed inside a
  // \code{try/catch} block since its execution may result in exceptions being
  // thrown.
  //
  // 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
  //
  // Of course, you could envision the addition of filters in between the
  // reader and the writer. Those filters could perform operations on the
  // vector image.
  //
  // Software Guide : EndLatex

  return EXIT_SUCCESS;
}