ITK  5.0.0
Insight Segmentation and Registration Toolkit
Examples/DataRepresentation/Image/ImageAdaptor2.cxx
/*=========================================================================
*
* 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
//
// This example illustrates how to use the \doxygen{ImageAdaptor}
// to access the individual components of an RGB image. In this case, we
// create an ImageAdaptor that will accept a RGB image as input and
// presents it as a scalar image. The pixel data
// will be taken directly from the red channel of the original image.
//
// \index{itk::ImageAdaptor!Instantiation}
// \index{itk::ImageAdaptor!Header}
//
// Software Guide : EndLatex
// Software Guide : BeginLatex
//
// As with the previous example, the bulk of the effort in creating the image
// adaptor is associated with the definition of the pixel accessor class. In
// this case, the accessor converts a RGB vector to a scalar containing the
// red channel component. Note that in the following, we do not need to define
// the \code{Set()} method since we only expect the adaptor to be used for
// reading data from the image.
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
class RedChannelPixelAccessor
{
public:
using InternalType = itk::RGBPixel<float>;
using ExternalType = float;
static ExternalType Get( const InternalType & input )
{
return static_cast<ExternalType>( input.GetRed() );
}
};
// Software Guide : EndCodeSnippet
// Software Guide : BeginLatex
//
// The \code{Get()} method simply calls the \code{GetRed()} method
// defined in the \doxygen{RGBPixel} class.
//
// Software Guide : EndLatex
//-------------------------
//
// Main code
//
//-------------------------
int main( int argc, char *argv[] )
{
if( argc < 3 )
{
std::cerr << "Usage: " << std::endl;
std::cerr << "ImageAdaptor2 inputRGBFileName outputRedChannelFileName" << std::endl;
return EXIT_FAILURE;
}
// Software Guide : BeginLatex
//
// Now we use the internal pixel type of the pixel accessor to define the
// input image type, and then proceed to instantiate the ImageAdaptor type.
//
// \index{PixelAccessor!RGB red channel}
// \index{itk::ImageAdaptor!RGB red channel}
// \index{ImageAdaptor!RGB red channel}
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
using InputPixelType = RedChannelPixelAccessor::InternalType;
constexpr unsigned int Dimension = 2;
using ImageAdaptorType = itk::ImageAdaptor< ImageType,
RedChannelPixelAccessor >;
ImageAdaptorType::Pointer adaptor = ImageAdaptorType::New();
// Software Guide : EndCodeSnippet
// Software Guide : BeginLatex
//
// We create an image reader and connect the output to the adaptor
// as before.
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
ReaderType::Pointer reader = ReaderType::New();
// Software Guide : EndCodeSnippet
reader->SetFileName( argv[1] );
reader->Update();
// Software Guide : BeginCodeSnippet
adaptor->SetImage( reader->GetOutput() );
// Software Guide : EndCodeSnippet
// Software Guide : BeginLatex
//
// We create an \doxygen{RescaleIntensityImageFilter} and an
// \doxygen{ImageFileWriter} to rescale the dynamic range of the pixel values
// and send the extracted channel to an image file. Note that the image type
// used for the rescaling filter is the \code{ImageAdaptorType} itself. That
// is, the adaptor type is used in the same context as an image type.
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
using OutputImageType = itk::Image< unsigned char, Dimension >;
using RescalerType = itk::RescaleIntensityImageFilter<
ImageAdaptorType,
OutputImageType >;
RescalerType::Pointer rescaler = RescalerType::New();
WriterType::Pointer writer = WriterType::New();
// Software Guide : EndCodeSnippet
writer->SetFileName( argv[2] );
// Software Guide : BeginLatex
//
// Now we connect the adaptor as the input to the rescaler and set the
// parameters for the intensity rescaling.
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
rescaler->SetOutputMinimum( 0 );
rescaler->SetOutputMaximum( 255 );
rescaler->SetInput( adaptor );
writer->SetInput( rescaler->GetOutput() );
// Software Guide : EndCodeSnippet
// Software Guide : BeginLatex
//
// Finally, we invoke the \code{Update()} method on the writer and take
// precautions to catch any exception that may be thrown during
// the execution of the pipeline.
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
try
{
writer->Update();
}
catch( itk::ExceptionObject & excp )
{
std::cerr << "Exception caught " << excp << std::endl;
return EXIT_FAILURE;
}
// Software Guide : EndCodeSnippet
// Software Guide : BeginLatex
//
// ImageAdaptors for the green and blue channels can easily be implemented by
// modifying the pixel accessor of the red channel and then using the
// new pixel accessor for instantiating the type of an image adaptor.
// The following define a green channel pixel accessor.
//
// \index{PixelAccessor!RGB green channel}
// \index{itk::ImageAdaptor!RGB green channel}
// \index{ImageAdaptor!RGB green channel}
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
class GreenChannelPixelAccessor
{
public:
using InternalType = itk::RGBPixel<float>;
using ExternalType = float;
static ExternalType Get( const InternalType & input )
{
return static_cast<ExternalType>( input.GetGreen() );
}
};
// Software Guide : EndCodeSnippet
// Software Guide : BeginLatex
//
// A blue channel pixel accessor is similarly defined.
//
// \index{PixelAccessor!RGB blue channel}
// \index{itk::ImageAdaptor!RGB blue channel}
// \index{ImageAdaptor!RGB blue channel}
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
class BlueChannelPixelAccessor
{
public:
using InternalType = itk::RGBPixel<float>;
using ExternalType = float;
static ExternalType Get( const InternalType & input )
{
return static_cast<ExternalType>( input.GetBlue() );
}
};
// Software Guide : EndCodeSnippet
// Software Guide : BeginLatex
//
// \begin{figure} \center
// \includegraphics[width=0.24\textwidth]{VisibleWomanEyeSlice}
// \includegraphics[width=0.24\textwidth]{VisibleWomanEyeSliceRedComponent}
// \includegraphics[width=0.24\textwidth]{VisibleWomanEyeSliceGreenComponent}
// \includegraphics[width=0.24\textwidth]{VisibleWomanEyeSliceBlueComponent}
// \itkcaption[Image Adaptor to RGB Image]{Using
// ImageAdaptor to extract the components of an RGB image. The
// image on the left is a subregion of the Visible Woman cryogenic data set.
// The red, green and blue components are shown from left to right as scalar
// images extracted with an ImageAdaptor.}
// \label{fig:ImageAdaptorToRGBImage}
// \end{figure}
//
//
// Figure~\ref{fig:ImageAdaptorToRGBImage} shows the result
// of extracting the red, green and blue components from a region of the
// Visible Woman cryogenic data set.
//
// Software Guide : EndLatex
return EXIT_SUCCESS;
}