text: /*=========================================================================
  
    Program:   Insight Segmentation & Registration Toolkit
    Module:    ImageReadWrite.cxx
    Language:  C++
    Date:      $Date$
    Version:   $Revision$
  
    Copyright (c) Insight Software Consortium. All rights reserved.
    See ITKCopyright.txt or http://www.itk.org/HTML/Copyright.htm for details.
  
       This software is distributed WITHOUT ANY WARRANTY; without even 
       the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR 
       PURPOSE.  See the above copyright notices for more information.
  
  =========================================================================*/
  #if defined(_MSC_VER)
  #pragma warning ( disable : 4786 )
  #endif
  
  //  Software Guide : BeginLatex
  //
  //  The classes responsible for reading and writing images are located at the
  //  beginning and end of the data processing pipeline. These classes are
  //  known as data sources (readers) and data sinks (writers).
  //  Generally speaking they are referred to as filters, although readers have
  //  no pipeline input and writers have no pipeline output.
  //
  //  The reading of images is managed by the class \doxygen{ImageFileReader}
  //  while writing is performed by the class \doxygen{ImageFileWriter}. These
  //  two classes are independent of any particular file format. The actual low
  //  level task of reading and writing specific file formats is done behind
  //  the scenes by a family of classes of type \doxygen{ImageIO}.
  //
  //  The first step for performing reading and writing is to include the
  //  following headers.
  //
  //  \index{itk::ImageFileReader|textbf}
  //  \index{itk::ImageFileReader!header}
  //
  //  \index{itk::ImageFileWriter|textbf}
  //  \index{itk::ImageFileWriter!header}
  //
  //  Software Guide : EndLatex
  
  // Software Guide : BeginCodeSnippet
  #include "itkImageFileReader.h"
  #include "itkImageFileWriter.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, a decision must be made about the type of pixel used to
    //  represent the image processed by the pipeline. Note that when reading
    //  and writing images, the pixel type of the image \textbf{is not
    //  necessarily} the same as the pixel type stored in the file.  Your
    //  choice of the pixel type (and hence template parameter) should be
    //  driven mainly by two considerations:
    //
    //  \begin{itemize}
    //  \item It should be possible to cast the file pixel type in the file to
    //  the pixel type you select. This casting will be performed using the
    //  standard C-language rules, so you will have to make sure that the
    //  conversion does not result in information being lost.
    //  \item The pixel type in memory should be appropriate to the type of
    //  processing you intended to apply on the images. 
    //  \end{itemize}
    //
    //  A typical selection for medical images is illustrated in
    //  the following lines.
    //
    //  Software Guide : EndLatex
  
    // Software Guide : BeginCodeSnippet
    typedef short      PixelType;
    const   unsigned int        Dimension = 2;
    typedef itk::Image< PixelType, Dimension >    ImageType;
    // Software Guide : EndCodeSnippet
  
  
    //  Software Guide : BeginLatex
    //
    //  Note that the dimension of the image in memory should match the one of
    //  the image in 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
    typedef itk::ImageFileReader< ImageType >  ReaderType;
    typedef itk::ImageFileWriter< ImageType >  WriterType;
    // 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}
    //
    //  Software Guide : EndLatex 
  
    // Software Guide : BeginCodeSnippet
    ReaderType::Pointer reader = ReaderType::New();
    WriterType::Pointer writer = WriterType::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()}
    //  \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
    //
    //  We can now connect these readers and writers to filters to create 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
    //
    //  At first view, this may seem as a quite useless program, but it is
    //  actually implementing a powerful file format conversion tool! The
    //  execution of the pipeline is triggered by the invocation of the
    //  \code{Update()} methods in one of the final objects. In this case, the final
    //  data pipeline object is the writer. It is a wise practice of defensive
    //  programming to insert any \code{Update()} call inside a \code{try/catch} block
    //  in case exceptions are thrown during the execution of the pipeline.
    //
    //  Software Guide : EndLatex 
  
  
    // Software Guide : BeginCodeSnippet
    try 
      { 
      writer->Update(); 
      } 
    catch( itk::ExceptionObject & err ) 
      { 
      std::cerr << "ExceptionObject caught !" << std::endl; 
      std::cerr << err << std::endl; 
      return EXIT_FAILURE;
      } 
    // Software Guide : EndCodeSnippet
  
  
    //  Software Guide : BeginLatex
    //
    //  Note that exceptions should only be caught by pieces of code that know
    //  what to do with them. In a typical application this \code{catch} block
    //  should probably reside on the GUI code. The action on the \code{catch}
    //  block could inform the user about the failure of the IO operation.
    //
    //  The IO architecture of the toolkit makes it possible to avoid explicit
    //  specification of the file format used to read or write
    //  images.\footnote{In this example no file format is specified; this
    //  program can be used as a general file conversion utility.}  The object
    //  factory mechanism enables the ImageFileReader and ImageFileWriter to
    //  determine (at run-time) with which file format it is working
    //  with. Typically, file formats are chosen based on the filename
    //  extension, but the architecture supports arbitrarily complex processes
    //  to determine whether a file can be read or written. Alternatively, the
    //  user can specify the data file format by explicit instantiation and
    //  assignment the appropriate \doxygen{ImageIO} subclass.
    //
    //  For historical reasons and as a convenience to the user, the
    //  \doxygen{ImageFileWriter} also has a Write() method that is aliased to
    //  the \code{Update()} method. You can in principle use either of them but
    //  \code{Update()} is recommended since Write() may be deprecated in the future.
    //
    //  Software Guide : EndLatex 
  
    return EXIT_SUCCESS;
  }
  