ITK  5.0.0
Insight Segmentation and Registration Toolkit
Examples/DataRepresentation/Image/ImageAdaptor4.cxx
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*
* Copyright Insight Software Consortium
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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
*
* http://www.apache.org/licenses/LICENSE-2.0.txt
*
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* 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
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*=========================================================================*/
// Software Guide : BeginCommandLineArgs
// INPUTS: {BrainProtonDensitySlice.png}
// OUTPUTS: {ImageAdaptorThresholdingA.png}
// ARGUMENTS: 180
// Software Guide : EndCommandLineArgs
//
// Software Guide : BeginCommandLineArgs
// INPUTS: {BrainProtonDensitySlice.png}
// OUTPUTS: {ImageAdaptorThresholdingB.png}
// ARGUMENTS: 220
// Software Guide : EndCommandLineArgs
// Software Guide : BeginLatex
//
// Image adaptors can also be used to perform simple pixel-wise computations
// on image data. The following example illustrates how to use the
// \doxygen{ImageAdaptor} for image thresholding.
//
// \index{itk::ImageAdaptor!Instantiation}
// \index{itk::ImageAdaptor!Header}
// \index{itk::ImageAdaptor!performing computation}
// \index{itk::PixelAccessor!with parameters}
// \index{itk::PixelAccessor!performing computation}
//
// Software Guide : EndLatex
// Software Guide : BeginLatex
//
// A pixel accessor for image thresholding requires that the accessor
// maintain the threshold value. Therefore, it must also implement the
// assignment operator to set this internal parameter.
//
// Software Guide : EndLatex
namespace itk
{
// Software Guide : BeginCodeSnippet
class ThresholdingPixelAccessor
{
public:
using InternalType = unsigned char;
using ExternalType = unsigned char;
ThresholdingPixelAccessor() {};
ExternalType Get( const InternalType & input ) const
{
return (input > m_Threshold) ? 1 : 0;
}
void SetThreshold( const InternalType threshold )
{
m_Threshold = threshold;
}
ThresholdingPixelAccessor &
operator=( const ThresholdingPixelAccessor & vpa ) = default;
private:
InternalType m_Threshold{0};
};
}
// Software Guide : EndCodeSnippet
// Software Guide : BeginLatex
//
// The \code{Get()} method returns one if the input pixel is above
// the threshold and zero otherwise. The assignment operator transfers
// the value of the threshold member
// variable from one instance of the pixel accessor to another.
//
// Software Guide : EndLatex
//-------------------------
//
// Main code
//
//-------------------------
int main( int argc, char *argv[] )
{
if( argc < 4 )
{
std::cerr << "Usage: " << std::endl;
std::cerr << "ImageAdaptor4 inputFileName outputBinaryFileName ";
std::cerr << " thresholdValue" << std::endl;
return EXIT_FAILURE;
}
// Software Guide : BeginLatex
//
// To create an image adaptor, we first instantiate an image type
// whose pixel type is the same as the internal pixel type of the pixel
// accessor.
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
using PixelType = itk::ThresholdingPixelAccessor::InternalType;
constexpr unsigned int Dimension = 2;
// Software Guide : EndCodeSnippet
// Software Guide : BeginLatex
//
// We instantiate the ImageAdaptor using the image type as the
// first template parameter and the pixel accessor as the second template
// parameter.
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
using ImageAdaptorType = itk::ImageAdaptor< ImageType,
itk::ThresholdingPixelAccessor >;
ImageAdaptorType::Pointer adaptor = ImageAdaptorType::New();
// Software Guide : EndCodeSnippet
// Software Guide : BeginLatex
//
// The threshold value is set from the command line. A threshold
// pixel accessor is created and connected to the image adaptor
// in the same manner as in the previous example.
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
itk::ThresholdingPixelAccessor accessor;
accessor.SetThreshold( std::stoi( argv[3] ) );
adaptor->SetPixelAccessor( accessor );
// Software Guide : EndCodeSnippet
// Software Guide : BeginLatex
//
// We create a reader to load the input image and connect the output
// of the reader as the input to the adaptor.
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
ReaderType::Pointer reader = ReaderType::New();
reader->SetFileName( argv[1] );
reader->Update();
adaptor->SetImage( reader->GetOutput() );
// Software Guide : EndCodeSnippet
using RescalerType = itk::RescaleIntensityImageFilter< ImageAdaptorType,
ImageType >;
RescalerType::Pointer rescaler = RescalerType::New();
WriterType::Pointer writer = WriterType::New();
writer->SetFileName( argv[2] );
rescaler->SetOutputMinimum( 0 );
rescaler->SetOutputMaximum( 255 );
rescaler->SetInput( adaptor );
writer->SetInput( rescaler->GetOutput() );
writer->Update();
// Software Guide : BeginLatex
//
// \begin{figure} \center
// \includegraphics[width=0.32\textwidth]{BrainProtonDensitySlice}
// \includegraphics[width=0.32\textwidth]{ImageAdaptorThresholdingA}
// \includegraphics[width=0.32\textwidth]{ImageAdaptorThresholdingB}
// \itkcaption[Image Adaptor for performing computations]{Using
// ImageAdaptor to perform a simple image computation. An
// ImageAdaptor is used to perform binary thresholding on
// the input image on the left. The center image was created using a
// threshold of 180, while the
// image on the right corresponds to a threshold of 220.}
// \label{fig:ImageAdaptorThresholding}
// \end{figure}
//
// As before, we rescale the emulated scalar image before writing it
// out to file.
// Figure~\ref{fig:ImageAdaptorThresholding} illustrates the result of
// applying the thresholding adaptor to a typical gray scale image using two
// different threshold values. Note that the same effect could have been
// achieved by using the \doxygen{BinaryThresholdImageFilter} but at the
// price of holding an extra copy of the image in memory.
//
// Software Guide : EndLatex
return EXIT_SUCCESS;
}