ITK  5.0.0
Insight Segmentation and Registration Toolkit
Examples/Filtering/ResampleImageFilter8.cxx
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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.
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*=========================================================================*/
// Software Guide : BeginLatex
//
// The following example illustrates how to use the
// \doxygen{WindowedSincInterpolateImageFunction} for resampling an image.
// This interpolator is in theory the best possible interpolator for
// reconstructing the continous values of a discrete image. In the spectral
// domain, this interpolator is performing the task of masking the central
// part of the spectrum of the sampled image, that in principle corresponds to
// the spectrumn of the continuous image before it was sampled into a discrete
// one. In this particular case an \doxygen{AffineTransform} is used to map
// the input space into the output space.
//
// \index{itk::AffineTransform!resampling}
//
// Software Guide : EndLatex
#include "itkImage.h"
// Software Guide : BeginLatex
//
// The header of the affine transform is included below.
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
// Software Guide : EndCodeSnippet
int main( int argc, char * argv[] )
{
if( argc < 4 )
{
std::cerr << "Usage: " << std::endl;
std::cerr << argv[0] << " inputImageFile outputImageFile degrees" << std::endl;
return EXIT_FAILURE;
}
constexpr unsigned int Dimension = 2;
using InputPixelType = unsigned char;
using OutputPixelType = unsigned char;
ReaderType::Pointer reader = ReaderType::New();
WriterType::Pointer writer = WriterType::New();
reader->SetFileName( argv[1] );
writer->SetFileName( argv[2] );
const double angleInDegrees = std::stod( argv[3] );
// Software Guide : BeginLatex
//
// The Resampling filter is instantiated and created just like in previous examples.
// The Transform is instantiated and connected to the resampling filter.
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
using FilterType = itk::ResampleImageFilter<
InputImageType, OutputImageType >;
FilterType::Pointer filter = FilterType::New();
TransformType::Pointer transform = TransformType::New();
filter->SetTransform( transform );
// Software Guide : EndCodeSnippet
// Software Guide : BeginLatex
//
// The salient feature of this example is the use of the
// \doxygen{WindowedSincInterpolateImageFunction}, which uses a truncated
// \emph{sinc} function in order to interpolate the resampled image.
//
// There is a close relationship between operations performed in the spatial
// domain and those applied in the spectral doman. For example, the action
// of truncating the \emph{sinc} function with a box function in the spatial
// domain will correspond to convolving its spectrum with the spectrum of a
// box function. Since the box function spectrum has an infinite support on
// the spectral domain, the result of the convolution will also have an
// infinite support on the spectral domain. Due to this effects, it is
// desirable to truncate the \emph{sinc} function by using a window that has
// a limited spectral support. Many different windows have been developed to
// this end in the domain of image processing. Among the most commonly used
// we have the \textbf{Hamming} window. We use here a Hamming window in
// order to define the truncation of the sinc function. The window is
// instantiated and its type is used in the instantiation of the
// WindowedSinc interpolator. The size of the window is one of the critical
// parameters of this class. The size must be decided at compilation time by
// using a \code{const integer} or an \code{enum}.
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
using BoundaryConditionType =
constexpr unsigned int WindowRadius = 5;
using WindowFunctionType =
InputImageType, WindowRadius, WindowFunctionType,
BoundaryConditionType, double >;
InterpolatorType::Pointer interpolator = InterpolatorType::New();
filter->SetInterpolator( interpolator );
filter->SetDefaultPixelValue( 100 );
// Software Guide : EndCodeSnippet
// Software Guide : BeginLatex
//
// The parameters of the output image are taken from the input image.
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
reader->Update();
const InputImageType::SpacingType&
spacing = reader->GetOutput()->GetSpacing();
origin = reader->GetOutput()->GetOrigin();
direction = reader->GetOutput()->GetDirection();
reader->GetOutput()->GetLargestPossibleRegion().GetSize();
filter->SetOutputOrigin( origin );
filter->SetOutputSpacing( spacing );
filter->SetOutputDirection( direction );
filter->SetSize( size );
// Software Guide : EndCodeSnippet
filter->SetInput( reader->GetOutput() );
writer->SetInput( filter->GetOutput() );
TransformType::OutputVectorType translation1;
const double imageCenterX = origin[0] + spacing[0] * size[0] / 2.0;
const double imageCenterY = origin[1] + spacing[1] * size[1] / 2.0;
translation1[0] = -imageCenterX;
translation1[1] = -imageCenterY;
transform->Translate( translation1 );
std::cout << "imageCenterX = " << imageCenterX << std::endl;
std::cout << "imageCenterY = " << imageCenterY << std::endl;
const double degreesToRadians = std::atan(1.0) / 45.0;
const double angle = angleInDegrees * degreesToRadians;
transform->Rotate2D( -angle, false );
TransformType::OutputVectorType translation2;
translation2[0] = imageCenterX;
translation2[1] = imageCenterY;
transform->Translate( translation2, false );
// Software Guide : BeginLatex
//
// The output of the resampling filter is connected to a writer and the
// execution of the pipeline is triggered by a writer update.
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
try
{
writer->Update();
}
catch( itk::ExceptionObject & excep )
{
std::cerr << "Exception catched !" << std::endl;
std::cerr << excep << std::endl;
}
// Software Guide : EndCodeSnippet
return EXIT_SUCCESS;
}