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/*=========================================================================
*
* 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 WarpImageFilter and a
// deformation field for resampling an image. This is typically done
// as the last step of a deformable registration algorithm.
//
// \index{itk::WarpImageFilter}
//
// Software Guide : EndLatex
#include "itkImage.h"
#include "itkImageFileReader.h"
#include "itkImageFileWriter.h"
// Software Guide : BeginCodeSnippet
#include "itkWarpImageFilter.h"
// Software Guide : EndCodeSnippet
int main( int argc, char * argv[] )
{
if( argc < 4 )
{
std::cerr << "Usage: " << std::endl;
std::cerr << argv[0] << " inputImageFile inputDisplacementField outputImageFile" << std::endl;
return EXIT_FAILURE;
}
const unsigned int Dimension = 2;
// Software Guide : BeginLatex
//
// The deformation field is represented as an image of vector pixel types. The
// dimension of the vectors is the same as the dimension of the input image.
// Each vector in the deformation field represents the distance between a
// geometric point in the input space and a point in the output space such that:
// \begin{equation}
// p_{in} = p_{out} + \text{distance}
// \end{equation}
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
typedef float VectorComponentType;
typedef itk::Vector< VectorComponentType, Dimension > VectorPixelType;
typedef itk::Image< VectorPixelType, Dimension > DisplacementFieldType;
typedef unsigned char PixelType;
typedef itk::Image< PixelType, Dimension > ImageType;
// Software Guide : EndCodeSnippet
typedef itk::ImageFileReader< ImageType > ReaderType;
typedef itk::ImageFileWriter< ImageType > WriterType;
// Software Guide : BeginLatex
//
// The field is read from a file, through a reader instantiated over the
// vector pixel types.
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
typedef itk::ImageFileReader< DisplacementFieldType > FieldReaderType;
// Software Guide : EndCodeSnippet
ReaderType::Pointer reader = ReaderType::New();
WriterType::Pointer writer = WriterType::New();
reader->SetFileName( argv[1] );
writer->SetFileName( argv[3] );
// Software Guide : BeginCodeSnippet
FieldReaderType::Pointer fieldReader = FieldReaderType::New();
fieldReader->SetFileName( argv[2] );
fieldReader->Update();
DisplacementFieldType::ConstPointer deformationField =
fieldReader->GetOutput();
// Software Guide : EndCodeSnippet
// Software Guide : BeginLatex
//
// The \doxygen{WarpImageFilter} is templated over the input image type,
// output image type and the deformation field type.
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
typedef itk::WarpImageFilter< ImageType,
ImageType,
DisplacementFieldType > FilterType;
FilterType::Pointer filter = FilterType::New();
// Software Guide : EndCodeSnippet
// Software Guide : BeginLatex
//
// Typically the mapped position does not correspond to an integer pixel position
// in the input image. Interpolation via an image function is used to compute
// values at non-integer positions.
// This is done via the \code{SetInterpolator()} method.
// \index{itk::Warp\-Image\-Filter!SetInterpolator()}
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
typedef itk::LinearInterpolateImageFunction<
ImageType, double > InterpolatorType;
InterpolatorType::Pointer interpolator = InterpolatorType::New();
filter->SetInterpolator( interpolator );
// Software Guide : EndCodeSnippet
// SoftwareGuide : BeginLatex
//
// The output image spacing and origin may be set via SetOutputSpacing(),
// SetOutputOrigin(). This is taken from the deformation field.
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
filter->SetOutputSpacing( deformationField->GetSpacing() );
filter->SetOutputOrigin( deformationField->GetOrigin() );
filter->SetOutputDirection( deformationField->GetDirection() );
filter->SetDisplacementField( deformationField );
// Software Guide : EndCodeSnippet
filter->SetInput( reader->GetOutput() );
writer->SetInput( filter->GetOutput() );
try
{
writer->Update();
}
catch( itk::ExceptionObject & excp )
{
std::cerr << "Exception thrown " << std::endl;
std::cerr << excp << std::endl;
}
return EXIT_SUCCESS;
}
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