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DataRepresentation/Image/Image2.cxx

00001 /*=========================================================================
00002 
00003   Program:   Insight Segmentation & Registration Toolkit
00004   Module:    $RCSfile: Image2.cxx,v $
00005   Language:  C++
00006   Date:      $Date: 2005/02/08 03:51:52 $
00007   Version:   $Revision: 1.19 $
00008 
00009   Copyright (c) Insight Software Consortium. All rights reserved.
00010   See ITKCopyright.txt or http://www.itk.org/HTML/Copyright.htm for details.
00011 
00012      This software is distributed WITHOUT ANY WARRANTY; without even 
00013      the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR 
00014      PURPOSE.  See the above copyright notices for more information.
00015 
00016 =========================================================================*/
00017 #if defined(_MSC_VER)
00018 #pragma warning ( disable : 4786 )
00019 #endif
00020 
00021 #include "itkImage.h"
00022 
00023 //  Software Guide : BeginLatex
00024 //
00025 //  The first thing required to read an image from a file is to include
00026 //  the header file of the \doxygen{ImageFileReader} class.
00027 //
00028 //  Software Guide : EndLatex 
00029 
00030 // Software Guide : BeginCodeSnippet
00031 #include "itkImageFileReader.h"
00032 // Software Guide : EndCodeSnippet
00033 
00034 int main( int , char * argv[])
00035 {
00036   // Software Guide : BeginLatex
00037   //
00038   // Then, the image type should be defined by specifying the
00039   // type used to represent pixels and the dimensions of the image.
00040   //
00041   // Software Guide : EndLatex 
00042 
00043   // Software Guide : BeginCodeSnippet
00044   typedef unsigned char          PixelType;
00045   const unsigned int             Dimension = 3;
00046 
00047   typedef itk::Image< PixelType, Dimension >   ImageType;
00048   // Software Guide : EndCodeSnippet
00049 
00050 
00051   // Software Guide : BeginLatex
00052   //
00053   // Using the image type, it is now possible to instantiate the image reader
00054   // class. The image type is used as a template parameter to define how the
00055   // data will be represented once it is loaded into memory. This type does
00056   // not have to correspond exactly to the type stored in the file. However,
00057   // a conversion based on C-style type casting is used, so the type chosen
00058   // to represent the data on disk must be sufficient to characterize it
00059   // accurately. Readers do not apply any transformation to the pixel data
00060   // other than casting from the pixel type of the file to the pixel type of
00061   // the ImageFileReader. The following illustrates a typical
00062   // instantiation of the ImageFileReader type.
00063   //
00064   // \index{itk::ImageFileReader!Instantiation}
00065   // \index{itk::Image!read}
00066   //
00067   // Software Guide : EndLatex 
00068 
00069   // Software Guide : BeginCodeSnippet
00070   typedef itk::ImageFileReader< ImageType >  ReaderType;
00071   // Software Guide : EndCodeSnippet
00072 
00073 
00074   // Software Guide : BeginLatex
00075   //
00076   // The reader type can now be used to create one reader object.  A
00077   // \doxygen{SmartPointer} (defined by the \code{::Pointer} notation) is used
00078   // to receive the reference to the newly created reader.  The \code{New()}
00079   // method is invoked to create an instance of the image reader.
00080   //
00081   // \index{itk::ImageFileReader!New()}
00082   // \index{itk::ImageFileReader!Pointer}
00083   //
00084   // Software Guide : EndLatex 
00085 
00086   // Software Guide : BeginCodeSnippet
00087   ReaderType::Pointer reader = ReaderType::New();
00088   // Software Guide : EndCodeSnippet
00089 
00090 
00091   // Software Guide : BeginLatex
00092   //
00093   // The minimum information required by the reader is the filename
00094   // of the image to be loaded in memory. This is provided through
00095   // the \code{SetFileName()} method. The file format here is inferred
00096   // from the filename extension. The user may also explicitly specify the
00097   // data format explicitly using the \doxygen{ImageIO} (See
00098   // Chapter~\ref{sec:ImagReadWrite} \pageref{sec:ImagReadWrite} for more
00099   // information
00100   //
00101   // \index{itk::ImageFileReader!SetFileName()}
00102   //
00103   // Software Guide : EndLatex 
00104 
00105   // Software Guide : BeginCodeSnippet
00106   const char * filename = argv[1];
00107   reader->SetFileName( filename );
00108   // Software Guide : EndCodeSnippet
00109 
00110 
00111   // Software Guide : BeginLatex
00112   //
00113   // Reader objects are referred to as pipeline source objects; they
00114   // respond to pipeline update requests and initiate the data flow in the
00115   // pipeline. The pipeline update mechanism ensures that the reader only
00116   // executes when a data request is made to the reader and the reader has
00117   // not read any data.  In the current example we explicitly invoke the
00118   // \code{Update()} method because the output of the reader is not connected
00119   // to other filters. In normal application the reader's output is connected
00120   // to the input of an image filter and the update invocation on the filter
00121   // triggers an update of the reader. The following line illustrates how an
00122   // explicit update is invoked on the reader.
00123   //
00124   // \index{itk::ImageFileReader!Update()}
00125   //
00126   // Software Guide : EndLatex 
00127 
00128   // Software Guide : BeginCodeSnippet
00129   reader->Update();
00130   // Software Guide : EndCodeSnippet
00131 
00132 
00133   // Software Guide : BeginLatex
00134   //
00135   // Access to the newly read image can be gained by calling the
00136   // \code{GetOutput()} method on the reader. This method can also be called
00137   // before the update request is sent to the reader.  The reference to the
00138   // image will be valid even though the image will be empty until the reader
00139   // actually executes.
00140   //
00141   // \index{itk::ImageFileReader!GetOutput()}
00142   //
00143   // Software Guide : EndLatex 
00144 
00145   // Software Guide : BeginCodeSnippet
00146   ImageType::Pointer image = reader->GetOutput();
00147   // Software Guide : EndCodeSnippet
00148 
00149   // Software Guide : BeginLatex
00150   //
00151   // Any attempt to access image data before the reader executes will yield
00152   // an image with no pixel data. It is likely that a program crash will 
00153   // result since the image will not have been properly initialized.
00154   //
00155   // Software Guide : EndLatex 
00156 
00157   return 0;
00158 }
00159 

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