For a complete description of the ITK Image Iterators and their API, please see the Iterators chapter in the ITK Software Guide. The ITK Software Guide is available in print and as a free .pdf download from http://www.itk.org.
/*========================================================================= Program: Insight Segmentation & Registration Toolkit Module: $RCSfile: ImageRegionIteratorWithIndex.cxx,v $ Language: C++ Date: $Date: 2009-03-16 23:38:19 $ Version: $Revision: 1.26 $ 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 : BeginCommandLineArgs // INPUTS: {VisibleWomanEyeSlice.png} // OUTPUTS: {ImageRegionIteratorWithIndexOutput.png} // Software Guide : EndCommandLineArgs // Software Guide : BeginLatex // // \index{Iterators!speed} // The ``WithIndex'' family of iterators was designed for algorithms that // use both the value and the location of image pixels in calculations. Unlike // \doxygen{ImageRegionIterator}, which calculates an index only when // asked for, \doxygen{ImageRegionIteratorWithIndex} maintains its // index location as a member variable that is updated during the increment or // decrement process. Iteration speed is penalized, but the index queries are // more efficient. // // \index{itk::ImageRegionIteratorWithIndex!example of using|(} // // The following example illustrates the use of // ImageRegionIteratorWithIndex. The algorithm mirrors // a 2D image across its $x$-axis (see \doxygen{FlipImageFilter} for an ND // version). The algorithm makes extensive use of the \code{GetIndex()} // method. // // We start by including the proper header file. // // Software Guide : EndLatex #include "itkImage.h" #include "itkRGBPixel.h" // Software Guide : BeginCodeSnippet #include "itkImageRegionIteratorWithIndex.h" // Software Guide : EndCodeSnippet #include "itkImageFileReader.h" #include "itkImageFileWriter.h" int main( int argc, char *argv[] ) { // Verify the number of parameters on the command line. if ( argc < 3 ) { std::cerr << "Missing parameters. " << std::endl; std::cerr << "Usage: " << std::endl; std::cerr << argv[0] << " inputImageFile outputImageFile" << std::endl; return -1; } // Software Guide : BeginLatex // // For this example, we will use an RGB pixel type so that we can process color // images. Like most other ITK image iterator, // ImageRegionIteratorWithIndex class expects the image type as its // single template parameter. // // Software Guide : EndLatex // Software Guide : BeginCodeSnippet const unsigned int Dimension = 2; typedef itk::RGBPixel< unsigned char > RGBPixelType; typedef itk::Image< RGBPixelType, Dimension > ImageType; typedef itk::ImageRegionIteratorWithIndex< ImageType > IteratorType; // Software Guide : EndCodeSnippet typedef itk::ImageFileReader< ImageType > ReaderType; typedef itk::ImageFileWriter< ImageType > WriterType; ImageType::ConstPointer inputImage; ReaderType::Pointer reader = ReaderType::New(); reader->SetFileName( argv[1] ); try { reader->Update(); inputImage = reader->GetOutput(); } catch ( itk::ExceptionObject &err) { std::cout << "ExceptionObject caught !" << std::endl; std::cout << err << std::endl; return -1; } // Software Guide : BeginLatex // // An \code{ImageType} smart pointer called \code{inputImage} points to the // output of the image reader. After updating the image reader, we can // allocate an output image of the same size, spacing, and origin as the // input image. // // Software Guide : EndLatex // Software Guide : BeginCodeSnippet ImageType::Pointer outputImage = ImageType::New(); outputImage->SetRegions( inputImage->GetRequestedRegion() ); outputImage->CopyInformation( inputImage ); outputImage->Allocate(); // Software Guide : EndCodeSnippet // Software Guide : BeginLatex // // Next we create the iterator that walks the output image. This algorithm // requires no iterator for the input image. // // Software Guide : EndLatex // Software Guide : BeginCodeSnippet IteratorType outputIt( outputImage, outputImage->GetRequestedRegion() ); // Software Guide : EndCodeSnippet // Software Guide: BeginLatex // // This axis flipping algorithm works by iterating through the output image, // querying the iterator for its index, and copying the value from the input // at an index mirrored across the $x$-axis. // // Software Guide : EndLatex // Software Guide : BeginCodeSnippet ImageType::IndexType requestedIndex = outputImage->GetRequestedRegion().GetIndex(); ImageType::SizeType requestedSize = outputImage->GetRequestedRegion().GetSize(); for ( outputIt.GoToBegin(); !outputIt.IsAtEnd(); ++outputIt) { ImageType::IndexType idx = outputIt.GetIndex(); idx[0] = requestedIndex[0] + requestedSize[0] - 1 - idx[0]; outputIt.Set( inputImage->GetPixel(idx) ); } // Software Guide : EndCodeSnippet WriterType::Pointer writer = WriterType::New(); writer->SetFileName( argv[2] ); writer->SetInput(outputImage); try { writer->Update(); } catch ( itk::ExceptionObject &err) { std::cout << "ExceptionObject caught !" << std::endl; std::cout << err << std::endl; return -1; } // Software Guide : BeginLatex // // Let's run this example on the image \code{VisibleWomanEyeSlice.png} found in // the \code{Examples/Data} directory. // Figure~\ref{fig:ImageRegionIteratorWithIndexExample} shows how the original // image has been mirrored across its $x$-axis in the output. // // \begin{figure} \center // \includegraphics[width=0.44\textwidth]{VisibleWomanEyeSlice.eps} // \includegraphics[width=0.44\textwidth]{ImageRegionIteratorWithIndexOutput.eps} // \itkcaption[Using the ImageRegionIteratorWithIndex]{Results of using // ImageRegionIteratorWithIndex to mirror an image across an axis. The original // image is shown at left. The mirrored output is shown at right.} // \label{fig:ImageRegionIteratorWithIndexExample} // \end{figure} // // \index{itk::ImageRegionIteratorWithIndex!example of using|)} // // Software Guide : EndLatex return 0; }