ITK  5.2.0
Insight Toolkit
Examples/Filtering/BinaryThresholdImageFilter.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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* http://www.apache.org/licenses/LICENSE-2.0.txt
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// Software Guide : BeginCommandLineArgs
// INPUTS: {BrainProtonDensitySlice.png}
// OUTPUTS: {BinaryThresholdImageFilterOutput.png}
// ARGUMENTS: 150 180 0 255
// Software Guide : EndCommandLineArgs
// Software Guide : BeginLatex
//
// \begin{figure}[h]
// \centering
// \includegraphics[width=7cm]{BinaryThresholdTransferFunction}
// \caption[BinaryThresholdImageFilter transfer function]
// {Transfer function of the BinaryThresholdImageFilter.
// \label{fig:BinaryThresholdTransferFunction}}
// \end{figure}
//
// This example illustrates the use of the binary threshold image filter.
// This filter is used to transform an image into a binary image by changing
// the pixel values according to the rule illustrated in
// Figure~\ref{fig:BinaryThresholdTransferFunction}. The user defines two
// thresholds---Upper and Lower---and two intensity values---Inside and
// Outside. For each pixel in the input image, the value of the pixel is
// compared with the lower and upper thresholds. If the pixel value is inside
// the range defined by $[\text{Lower},\text{Upper}]$ the output pixel is
// assigned the InsideValue. Otherwise the output pixels are assigned to the
// OutsideValue. Thresholding is commonly applied as the last operation of a
// segmentation pipeline.
//
// \index{itk::Binary\-Threshold\-Image\-Filter!Instantiation}
// \index{itk::Binary\-Threshold\-Image\-Filter!Header}
//
// The first step required to use the \doxygen{BinaryThresholdImageFilter} is
// to include its header file.
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
// Software Guide : EndCodeSnippet
#include "itkImage.h"
int
main(int argc, char * argv[])
{
if (argc < 7)
{
std::cerr << "Usage: " << argv[0];
std::cerr << " inputImageFile outputImageFile ";
std::cerr << " lowerThreshold upperThreshold ";
std::cerr << " outsideValue insideValue " << std::endl;
return EXIT_FAILURE;
}
// Software Guide : BeginLatex
//
// The next step is to decide which pixel types to use for the input and
// output images.
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
using InputPixelType = unsigned char;
using OutputPixelType = unsigned char;
// Software Guide : EndCodeSnippet
// Software Guide : BeginLatex
//
// The input and output image types are now defined using their respective
// pixel types and dimensions.
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
using InputImageType = itk::Image<InputPixelType, 2>;
using OutputImageType = itk::Image<OutputPixelType, 2>;
// Software Guide : EndCodeSnippet
// Software Guide : BeginLatex
//
// The filter type can be instantiated using the input and output image
// types defined above.
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
using FilterType =
// Software Guide : EndCodeSnippet
// Software Guide : BeginLatex
//
// An \doxygen{ImageFileReader} class is also instantiated in order to read
// image data from a file. (See Section \ref{sec:IO} on page
// \pageref{sec:IO} for more information about reading
// and writing data.)
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
// Software Guide : EndCodeSnippet
// Software Guide : BeginLatex
//
// An \doxygen{ImageFileWriter} is instantiated in order to write the output
// image to a file.
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
// Software Guide : EndCodeSnippet
// Software Guide : BeginLatex
//
// Both the filter and the reader are created by invoking their
// \code{New()} methods and assigning the result to
// \doxygen{SmartPointer}s.
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
ReaderType::Pointer reader = ReaderType::New();
FilterType::Pointer filter = FilterType::New();
// Software Guide : EndCodeSnippet
WriterType::Pointer writer = WriterType::New();
writer->SetInput(filter->GetOutput());
reader->SetFileName(argv[1]);
// Software Guide : BeginLatex
//
// The image obtained with the reader is passed as input to the
// BinaryThresholdImageFilter.
//
// \index{itk::Binary\-Threshold\-Image\-Filter!SetInput()}
// \index{itk::FileImageReader!GetOutput()}
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
filter->SetInput(reader->GetOutput());
// Software Guide : EndCodeSnippet
// Software Guide : BeginLatex
//
// The method \code{SetOutsideValue()} defines the intensity value to be
// assigned to those pixels whose intensities are outside the range defined
// by the lower and upper thresholds. The method \code{SetInsideValue()}
// defines the intensity value to be assigned to pixels with intensities
// falling inside the threshold range.
//
// \index{itk::Binary\-Threshold\-Image\-Filter!SetOutsideValue()}
// \index{itk::Binary\-Threshold\-Image\-Filter!SetInsideValue()}
// \index{SetOutsideValue()!itk::Binary\-Threshold\-Image\-Filter}
// \index{SetInsideValue()!itk::Binary\-Threshold\-Image\-Filter}
//
// Software Guide : EndLatex
const OutputPixelType outsideValue = std::stoi(argv[5]);
const OutputPixelType insideValue = std::stoi(argv[6]);
// Software Guide : BeginCodeSnippet
filter->SetOutsideValue(outsideValue);
filter->SetInsideValue(insideValue);
// Software Guide : EndCodeSnippet
// Software Guide : BeginLatex
//
// The methods \code{SetLowerThreshold()} and \code{SetUpperThreshold()}
// define the range of the input image intensities that will be transformed
// into the \code{InsideValue}. Note that the lower and upper thresholds
// are values of the type of the input image pixels, while the inside and
// outside values are of the type of the output image pixels.
//
// Software Guide : EndLatex
const InputPixelType lowerThreshold = std::stoi(argv[3]);
const InputPixelType upperThreshold = std::stoi(argv[4]);
// Software Guide : BeginCodeSnippet
filter->SetLowerThreshold(lowerThreshold);
filter->SetUpperThreshold(upperThreshold);
// Software Guide : EndCodeSnippet
// Software Guide : BeginLatex
//
// The execution of the filter is triggered by invoking the \code{Update()}
// method. If the filter's output has been passed as input to subsequent
// filters, the \code{Update()} call on any downstream filters in the
// pipeline will indirectly trigger the update of this filter.
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
filter->Update();
// Software Guide : EndCodeSnippet
// Software Guide : BeginLatex
//
// \begin{figure}
// \center
// \includegraphics[width=0.44\textwidth]{BrainProtonDensitySlice}
// \includegraphics[width=0.44\textwidth]{BinaryThresholdImageFilterOutput}
// \itkcaption[BinaryThresholdImageFilter output]{Effect of the
// BinaryThresholdImageFilter on a slice from a MRI proton density image of
// the brain.} \label{fig:BinaryThresholdImageFilterInputOutput}
// \end{figure}
//
// Figure \ref{fig:BinaryThresholdImageFilterInputOutput} illustrates the
// effect of this filter on a MRI proton density image of the brain. This
// figure shows the limitations of the filter for performing segmentation
// by itself. These limitations are particularly noticeable in noisy images
// and in images lacking spatial uniformity as is the case with MRI due to
// field bias.
//
// \relatedClasses
// \begin{itemize}
// \item \doxygen{ThresholdImageFilter}
// \end{itemize}
//
// Software Guide : EndLatex
writer->SetFileName(argv[2]);
writer->Update();
return EXIT_SUCCESS;
}
itk::BinaryThresholdImageFilter
Binarize an input image by thresholding.
Definition: itkBinaryThresholdImageFilter.h:139
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
itkImageFileWriter.h
itkBinaryThresholdImageFilter.h
itk::Image
Templated n-dimensional image class.
Definition: itkImage.h:86