ITK  5.2.0
Insight Toolkit
Examples/IO/CovariantVectorImageRead.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.
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// Software Guide : BeginLatex
//
// This example illustrates how to read an image whose pixel type is
// \code{CovariantVector}. For practical purposes this example is applicable
// to images of pixel type \doxygen{Vector}, \doxygen{Point} and
// \doxygen{FixedArray}. These pixel types are similar in that they are all
// arrays of fixed size in which the components have the same representation
// type.
//
// In this example we are reading a gradient image from a file (written in
// the previous example) and computing its magnitude using the
// \doxygen{VectorMagnitudeImageFilter}. Note that this filter is
// different from the \doxygen{GradientMagnitudeImageFilter} which actually
// takes a scalar image as input and computes the magnitude of its gradient.
// The VectorMagnitudeImageFilter class takes an image of vector
// pixel type as input and computes pixel-wise the magnitude of each vector.
//
// Let's start by including the relevant header files.
//
// \index{ImageFileRead!Vector images}
// \index{VectorMagnitudeImageFilter!header}
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
// Software Guide : EndCodeSnippet
#include "itkImage.h"
int
main(int argc, char ** argv)
{
// Verify the number of parameters in the command line
if (argc < 3)
{
std::cerr << "Usage: " << std::endl;
std::cerr << argv[0] << " inputImageFile outputVectorImageFile "
<< std::endl;
return EXIT_FAILURE;
}
// Software Guide : BeginLatex
//
// We read an image of \doxygen{CovariantVector} pixels and compute pixel
// magnitude to produce an image where each pixel is of type
// \code{unsigned short}. The components of the CovariantVector
// are selected to be \code{float} here. Notice that a renormalization is
// required in order to map the dynamic range of the magnitude values into
// the range of the output pixel type. The
// \doxygen{RescaleIntensityImageFilter} is used to achieve this.
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
using ComponentType = float;
constexpr unsigned int Dimension = 2;
using MagnitudePixelType = float;
using OutputPixelType = unsigned short;
using InputImageType = itk::Image<InputPixelType, Dimension>;
using MagnitudeImageType = itk::Image<MagnitudePixelType, Dimension>;
using OutputImageType = itk::Image<OutputPixelType, Dimension>;
// Software Guide : EndCodeSnippet
// Software Guide : BeginLatex
//
// The \doxygen{ImageFileReader} and \doxygen{ImageFileWriter}
// are instantiated using the image types.
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
// Software Guide : EndCodeSnippet
// Software Guide : BeginLatex
//
// The VectorMagnitudeImageFilter is instantiated using the
// input and output image types. A filter object is created with the
// \code{New()} method and assigned to a \doxygen{SmartPointer}.
//
// \index{VectorMagnitudeImageFilter!Instantiation}
// \index{VectorMagnitudeImageFilter!New()}
// \index{VectorMagnitudeImageFilter!Pointer}
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
using FilterType =
FilterType::Pointer filter = FilterType::New();
// Software Guide : EndCodeSnippet
// Software Guide : BeginLatex
//
// The RescaleIntensityImageFilter class is instantiated next.
//
// \index{RescaleIntensityImageFilter!Instantiation}
// \index{RescaleIntensityImageFilter!New()}
// \index{RescaleIntensityImageFilter!Pointer}
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
using RescaleFilterType =
RescaleFilterType::Pointer rescaler = RescaleFilterType::New();
// Software Guide : EndCodeSnippet
// Software Guide : BeginLatex
//
// In the following the minimum and maximum values for the output image
// are specified. Note the use of the \doxygen{NumericTraits} class which
// allows us to define a number of type-related constants in a generic
// way. The use of traits is a fundamental characteristic of generic
// programming~\cite{Austern1999,Alexandrescu2001}.
//
// \index{RescaleIntensityImageFilter!SetOutputMinimum()}
// \index{RescaleIntensityImageFilter!SetOutputMaximum()}
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
rescaler->SetOutputMinimum(itk::NumericTraits<OutputPixelType>::min());
rescaler->SetOutputMaximum(itk::NumericTraits<OutputPixelType>::max());
// Software Guide : EndCodeSnippet
// Software Guide : BeginLatex
//
// Below, we create the reader and writer using the \code{New()} method and
// assign the result to a \doxygen{SmartPointer}.
//
// \index{itk::ImageFileReader!New()}
// \index{itk::ImageFileWriter!New()}
// \index{itk::ImageFileReader!SmartPointer}
// \index{itk::ImageFileWriter!SmartPointer}
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
ReaderType::Pointer reader = ReaderType::New();
WriterType::Pointer writer = WriterType::New();
// Software Guide : EndCodeSnippet
// Here we recover the file names from the command line arguments
//
const char * inputFilename = argv[1];
const char * outputFilename = argv[2];
// Software Guide : BeginLatex
//
// The name of the file to be read or written is passed with the
// \code{SetFileName()} method.
//
// \index{itk::ImageFileReader!SetFileName()}
// \index{itk::ImageFileWriter!SetFileName()}
// \index{SetFileName()!itk::ImageFileReader}
// \index{SetFileName()!itk::ImageFileWriter}
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
reader->SetFileName(inputFilename);
writer->SetFileName(outputFilename);
// Software Guide : EndCodeSnippet
// Software Guide : BeginLatex
//
// Below we connect the reader, filter and writer to form the data
// processing pipeline.
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
filter->SetInput(reader->GetOutput());
rescaler->SetInput(filter->GetOutput());
writer->SetInput(rescaler->GetOutput());
// Software Guide : EndCodeSnippet
// Software Guide : BeginLatex
//
// Finally we execute the pipeline by invoking \code{Update()} on the
// writer. The call is placed in a \code{try/catch} block in case
// exceptions are thrown.
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
try
{
writer->Update();
}
catch (const itk::ExceptionObject & err)
{
std::cerr << "ExceptionObject caught !" << std::endl;
std::cerr << err << std::endl;
return EXIT_FAILURE;
}
// Software Guide : EndCodeSnippet
return EXIT_SUCCESS;
}
itk::VectorMagnitudeImageFilter
Take an image of vectors as input and produce an image with the magnitude of those vectors.
Definition: itkVectorMagnitudeImageFilter.h:75
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
itkRescaleIntensityImageFilter.h
itkVectorMagnitudeImageFilter.h
itkImageFileWriter.h
itk::NumericTraits
Define additional traits for native types such as int or float.
Definition: itkNumericTraits.h:58
itk::CovariantVector
A templated class holding a n-Dimensional covariant vector.
Definition: itkCovariantVector.h:70
itk::RescaleIntensityImageFilter
Applies a linear transformation to the intensity levels of the input Image.
Definition: itkRescaleIntensityImageFilter.h:154
itk::Image
Templated n-dimensional image class.
Definition: itkImage.h:86
itk::GTest::TypedefsAndConstructors::Dimension2::Dimension
constexpr unsigned int Dimension
Definition: itkGTestTypedefsAndConstructors.h:44