ITK  5.2.0
Insight Toolkit
Examples/Iterators/ImageLinearIteratorWithIndex.cxx
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* Copyright NumFOCUS
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* 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
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*
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// 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()}} Moves the iterator to
// \emph{one past} the last valid pixel of the current line.
//
// \index{itk::ImageLinearIteratorWithIndex!GoToReverseBeginOfLine()}
//
// \item \textbf{\code{GoToReverseBeginOfLine()}} Moves 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
// Software Guide : EndCodeSnippet
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 EXIT_FAILURE;
}
// 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
constexpr unsigned int Dimension = 2;
using RGBPixelType = itk::RGBPixel<unsigned char>;
// Software Guide : BeginCodeSnippet
// Software Guide : EndCodeSnippet
using ReaderType = itk::ImageFileReader<ImageType>;
using WriterType = itk::ImageFileWriter<ImageType>;
ImageType::ConstPointer inputImage;
ReaderType::Pointer reader = ReaderType::New();
reader->SetFileName(argv[1]);
try
{
reader->Update();
inputImage = reader->GetOutput();
}
catch (const itk::ExceptionObject & err)
{
std::cerr << "ExceptionObject caught a !" << std::endl;
std::cerr << err << std::endl;
return EXIT_FAILURE;
}
// 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 (const itk::ExceptionObject & err)
{
std::cerr << "ExceptionObject caught !" << std::endl;
std::cerr << err << std::endl;
return EXIT_FAILURE;
}
// 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 EXIT_SUCCESS;
}
itk::RGBPixel
Represent Red, Green and Blue components for color images.
Definition: itkRGBPixel.h:58
itkRGBPixel.h
itk::ImageLinearIteratorWithIndex
A multi-dimensional image iterator that visits image pixels within a region in a "scan-line" order.
Definition: itkImageLinearIteratorWithIndex.h:67
itkImageFileReader.h
itkImage.h
itk::ImageFileReader
Data source that reads image data from a single file.
Definition: itkImageFileReader.h:75
itk::ImageFileWriter
Writes image data to a single file.
Definition: itkImageFileWriter.h:87
itkImageLinearIteratorWithIndex.h
itkImageFileWriter.h
itk::Image
Templated n-dimensional image class.
Definition: itkImage.h:86
itk::GTest::TypedefsAndConstructors::Dimension2::Dimension
constexpr unsigned int Dimension
Definition: itkGTestTypedefsAndConstructors.h:44
itk::ImageLinearConstIteratorWithIndex
A multi-dimensional image iterator that visits image pixels within a region in a "scan-line" order.
Definition: itkImageLinearConstIteratorWithIndex.h:101