/*========================================================================= Program: Insight Segmentation & Registration Toolkit Module: $RCSfile: Image2.cxx,v $ Language: C++ Date: $Date: 2010-02-18 23:49:30 $ Version: $Revision: 1.21 $ 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 #include "itkImage.h" // Software Guide : BeginLatex // // The first thing required to read an image from a file is to include // the header file of the \doxygen{ImageFileReader} class. // // Software Guide : EndLatex // Software Guide : BeginCodeSnippet #include "itkImageFileReader.h" // Software Guide : EndCodeSnippet int main( int , char * argv[]) { // Software Guide : BeginLatex // // Then, the image type should be defined by specifying the // type used to represent pixels and the dimensions of the image. // // Software Guide : EndLatex // Software Guide : BeginCodeSnippet typedef unsigned char PixelType; const unsigned int Dimension = 3; typedef itk::Image< PixelType, Dimension > ImageType; // Software Guide : EndCodeSnippet // Software Guide : BeginLatex // // Using the image type, it is now possible to instantiate the image reader // class. The image type is used as a template parameter to define how the // data will be represented once it is loaded into memory. This type does // not have to correspond exactly to the type stored in the file. However, // a conversion based on C-style type casting is used, so the type chosen // to represent the data on disk must be sufficient to characterize it // accurately. Readers do not apply any transformation to the pixel data // other than casting from the pixel type of the file to the pixel type of // the ImageFileReader. The following illustrates a typical // instantiation of the ImageFileReader type. // // \index{itk::ImageFileReader!Instantiation} // \index{itk::Image!read} // // Software Guide : EndLatex // Software Guide : BeginCodeSnippet typedef itk::ImageFileReader< ImageType > ReaderType; // Software Guide : EndCodeSnippet // Software Guide : BeginLatex // // The reader type can now be used to create one reader object. A // \doxygen{SmartPointer} (defined by the \code{::Pointer} notation) is used // to receive the reference to the newly created reader. The \code{New()} // method is invoked to create an instance of the image reader. // // \index{itk::ImageFileReader!New()} // \index{itk::ImageFileReader!Pointer} // // Software Guide : EndLatex // Software Guide : BeginCodeSnippet ReaderType::Pointer reader = ReaderType::New(); // Software Guide : EndCodeSnippet // Software Guide : BeginLatex // // The minimum information required by the reader is the filename // of the image to be loaded in memory. This is provided through // the \code{SetFileName()} method. The file format here is inferred // from the filename extension. The user may also explicitly specify the // data format explicitly using the \doxygen{ImageIO} (See // Chapter~\ref{sec:ImagReadWrite} \pageref{sec:ImagReadWrite} for more // information). // // \index{itk::ImageFileReader!SetFileName()} // // Software Guide : EndLatex // Software Guide : BeginCodeSnippet const char * filename = argv[1]; reader->SetFileName( filename ); // Software Guide : EndCodeSnippet // Software Guide : BeginLatex // // Reader objects are referred to as pipeline source objects; they // respond to pipeline update requests and initiate the data flow in the // pipeline. The pipeline update mechanism ensures that the reader only // executes when a data request is made to the reader and the reader has // not read any data. In the current example we explicitly invoke the // \code{Update()} method because the output of the reader is not connected // to other filters. In normal application the reader's output is connected // to the input of an image filter and the update invocation on the filter // triggers an update of the reader. The following line illustrates how an // explicit update is invoked on the reader. // // \index{itk::ImageFileReader!Update()} // // Software Guide : EndLatex // Software Guide : BeginCodeSnippet reader->Update(); // Software Guide : EndCodeSnippet // Software Guide : BeginLatex // // Access to the newly read image can be gained by calling the // \code{GetOutput()} method on the reader. This method can also be called // before the update request is sent to the reader. The reference to the // image will be valid even though the image will be empty until the reader // actually executes. // // \index{itk::ImageFileReader!GetOutput()} // // Software Guide : EndLatex // Software Guide : BeginCodeSnippet ImageType::Pointer image = reader->GetOutput(); // Software Guide : EndCodeSnippet // Software Guide : BeginLatex // // Any attempt to access image data before the reader executes will yield // an image with no pixel data. It is likely that a program crash will // result since the image will not have been properly initialized. // // Software Guide : EndLatex return 0; }