ImageLinearIteratorWithIndex.cxx

MORE INFORMATION

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.

See Also

ImageConstIterator

ConditionalConstIterator

ConstNeighborhoodIterator

ConstShapedNeighborhoodIterator

ConstSliceIterator

CorrespondenceDataStructureIterator

FloodFilledFunctionConditionalConstIterator

FloodFilledImageFunctionConditionalConstIterator

FloodFilledImageFunctionConditionalIterator

FloodFilledSpatialFunctionConditionalConstIterator

FloodFilledSpatialFunctionConditionalIterator

ImageConstIterator

ImageConstIteratorWithIndex

ImageIterator

ImageIteratorWithIndex

ImageLinearConstIteratorWithIndex

ImageLinearIteratorWithIndex

ImageRandomConstIteratorWithIndex

ImageRandomIteratorWithIndex

ImageRegionConstIterator

ImageRegionConstIteratorWithIndex

ImageRegionExclusionConstIteratorWithIndex

ImageRegionExclusionIteratorWithIndex

ImageRegionIterator

ImageRegionIteratorWithIndex

ImageRegionReverseConstIterator

ImageRegionReverseIterator

ImageReverseConstIterator

ImageReverseIterator

ImageSliceConstIteratorWithIndex

ImageSliceIteratorWithIndex

NeighborhoodIterator

PathConstIterator

PathIterator

ShapedNeighborhoodIterator

SliceIterator

ImageConstIteratorWithIndex

/*=========================================================================
 *
 *  Copyright Insight Software Consortium
 *
 *  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
 *
 *         http://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
//
// The \doxygen{ImageLinearIteratorWithIndex} is designed for line-by-line
// processing of an image.  It walks a linear path along a selected image
// direction parallel to one of the coordinate axes of the image. This
// iterator conceptually breaks an image into a set of parallel lines
// that span the selected image dimension.
//
// \index{Iterators!and image lines}
//
// Like all image iterators, movement of the
// ImageLinearIteratorWithIndex is constrained within an
// image region $R$.  The line $\ell$ through which the iterator moves is
// defined by selecting a direction and an origin.   The line $\ell$
// extends from the origin to the upper boundary of $R$. The origin can be
// moved to any position along the lower boundary of $R$.
//
// Several additional methods are defined for this iterator to control movement
// of the iterator along the line $\ell$ and movement of the origin of $\ell$.
//
// %Might need a figure here to describe this iterator.
//
// \begin{itemize}
//
// \index{itk::ImageLinearIteratorWithIndex!NextLine()}
//
// \item \textbf{\code{NextLine()}} Moves the iterator to the beginning pixel
// location of the next line in the image.  The origin of the next line is
// determined by incrementing the current origin along the fastest increasing
// dimension of the subspace of the image that excludes the selected dimension.
//
//
// \index{itk::ImageLinearIteratorWithIndex!PreviousLine()}
//
// \item \textbf{\code{PreviousLine()}} Moves the iterator to the \emph{last valid
// pixel location} in the previous line. The origin of the previous line is
// determined by decrementing the current origin along the fastest increasing
// dimension of the subspace of the image that excludes the selected dimension.
//
// \index{itk::ImageLinearIteratorWithIndex!GoToBeginOfLine()}
//
// \item \textbf{\code{GoToBeginOfLine()}} Moves the iterator to the beginning
// pixel of the current line.
//
// \index{itk::ImageLinearIteratorWithIndex!GoToEndOfLine()}
//
// \item \textbf{\code{GoToEndOfLine()}}  Move the iterator to
// \emph{one past} the last valid pixel of the current line.
//
// \index{itk::ImageLinearIteratorWithIndex!GoToReverseBeginOfLine()}
//
// \item \textbf{\code{GoToReverseBeginOfLine()}}  Move the iterator
// to \emph{the last valid pixel} of the current line.
//
// \index{itk::ImageLinearIteratorWithIndex!IsAtReverseEndOfLine()}
//
// \item \textbf{\code{IsAtReverseEndOfLine()}}
// Returns true if the iterator points
// to \emph{one position before} the beginning pixel of the current line.
//
// \index{itk::ImageLinearIteratorWithIndex!IsAtEndOfLine()}
//
// \item \textbf{\code{IsAtEndOfLine()}}
// Returns true if the iterator points to
// \emph{one position past} the last valid pixel of the current line.
// \end{itemize}
//
// The following code example shows how to use the
// ImageLinearIteratorWithIndex.  It implements the same algorithm as
// in the previous example, flipping an image across its $x$-axis.  Two line
// iterators are iterated in opposite directions across the $x$-axis.
// After each line is traversed, the iterator origins are stepped along
// the $y$-axis to the
// next line.
//
// \index{itk::ImageLinearIteratorWithIndex!example of using|(}
//
// Headers for both the const and non-const versions are needed.
//
// Software Guide : EndLatex

#include "itkImage.h"
#include "itkRGBPixel.h"
// Software Guide : BeginCodeSnippet
#include "itkImageLinearIteratorWithIndex.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
//
// The RGB image and pixel types are defined as in the previous example.  The
// ImageLinearIteratorWithIndex class and its const version each have
// single template parameters, the image type.
//
// Software Guide : EndLatex

  const unsigned int Dimension = 2;

  typedef itk::RGBPixel< unsigned char >        RGBPixelType;
  typedef itk::Image< RGBPixelType, Dimension > ImageType;

// Software Guide : BeginCodeSnippet
  typedef itk::ImageLinearIteratorWithIndex< ImageType >       IteratorType;
  typedef itk::ImageLinearConstIteratorWithIndex< ImageType >  ConstIteratorType;
// 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 a !" << std::endl;
    std::cout << err << std::endl;
    return -1;
    }

// Software Guide : BeginLatex
//
// After reading the input image, we allocate an output image that of the same
// size, spacing, and origin.
//
// 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 two iterators.  The const iterator walks the input image,
// and the non-const iterator walks the output image.  The iterators are
// initialized over the same region.  The direction of iteration is set to 0,
// the $x$ dimension.
//
// Software Guide : EndLatex

// Software Guide : BeginCodeSnippet
  ConstIteratorType inputIt( inputImage, inputImage->GetRequestedRegion() );
  IteratorType outputIt( outputImage, inputImage->GetRequestedRegion() );

  inputIt.SetDirection(0);
  outputIt.SetDirection(0);
// Software Guide : EndCodeSnippet

// Software Guide: BeginLatex
//
// Each line in the input is copied to the output.  The input iterator moves
// forward across columns while the output iterator moves backwards.
//
// Software Guide : EndLatex

// Software Guide : BeginCodeSnippet
  for ( inputIt.GoToBegin(),  outputIt.GoToBegin(); ! inputIt.IsAtEnd();
        outputIt.NextLine(),  inputIt.NextLine())
    {
    inputIt.GoToBeginOfLine();
    outputIt.GoToEndOfLine();
    while ( ! inputIt.IsAtEndOfLine() )
      {
      --outputIt;
      outputIt.Set( inputIt.Get() );
      ++inputIt;
      }
    }
// 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
//
// Running this example on \code{VisibleWomanEyeSlice.png} produces
// the same output image shown in
// Figure~\ref{fig:ImageRegionIteratorWithIndexExample}.
//
// \index{itk::ImageLinearIteratorWithIndex!example of using|)}
// Software Guide : EndLatex

  return 0;
}