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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.
*
*=========================================================================*/
#ifndef itkExponentialDisplacementFieldImageFilter_h
#define itkExponentialDisplacementFieldImageFilter_h
#include "itkDivideImageFilter.h"
#include "itkCastImageFilter.h"
#include "itkWarpVectorImageFilter.h"
#include "itkVectorLinearInterpolateNearestNeighborExtrapolateImageFunction.h"
#include "itkAddImageFilter.h"
namespace itk
{
/** \class ExponentialDisplacementFieldImageFilter
* \brief Computes a diffeomorphic displacement field as the Lie group
* exponential of a vector field.
*
* ExponentialDisplacementFieldImageFilter takes a 'smooth' vector field
* as input and computes the displacement field that is its exponential.
*
* Given that both the input and output displacement field are represented as
* discrete images with pixel type vector, the exponential will be only an
* estimation and will probably not correspond to a perfect exponential. The
* precision of the exponential can be improved at the price of increasing the
* computation time (number of iterations).
*
* The method used for computing the exponential displacement field is
* an iterative scaling and squaring (cf Arsigny et al., "A
* Log-Euclidean Framework for Statistics on Diffeomorphisms", MICCAI'06).
*
* \f[
* exp(\Phi) = exp( \frac{\Phi}{2^N} )^{2^N}
* \f]
*
*
* This filter expects both the input and output images to be of pixel type
* Vector.
*
* \author Tom Vercauteren, INRIA & Mauna Kea Technologies
*
* This implementation was taken from the Insight Journal paper:
* https://hdl.handle.net/1926/510
*
* \ingroup ITKDisplacementField
*/
template< typename TInputImage, typename TOutputImage >
class ITK_TEMPLATE_EXPORT ExponentialDisplacementFieldImageFilter:
public ImageToImageFilter< TInputImage, TOutputImage >
{
public:
/** Standard class typedefs. */
typedef ExponentialDisplacementFieldImageFilter Self;
typedef ImageToImageFilter< TInputImage, TOutputImage > Superclass;
typedef SmartPointer< Self > Pointer;
typedef SmartPointer< const Self > ConstPointer;
/** Method for creation through the object factory. */
itkNewMacro(Self);
/** Run-time type information (and related methods). */
itkTypeMacro(ExponentialDisplacementFieldImageFilter, ImageToImageFilter);
/** Some convenient typedefs. */
typedef TInputImage InputImageType;
typedef typename InputImageType::Pointer InputImagePointer;
typedef typename InputImageType::ConstPointer InputImageConstPointer;
typedef typename InputImageType::PixelType InputPixelType;
typedef typename InputPixelType::RealValueType InputPixelRealValueType;
typedef TOutputImage OutputImageType;
typedef typename OutputImageType::Pointer OutputImagePointer;
typedef typename OutputImageType::PixelType OutputPixelType;
/** Specify the maximum number of iteration. */
itkSetMacro(MaximumNumberOfIterations, unsigned int);
itkGetConstMacro(MaximumNumberOfIterations, unsigned int);
/** If AutomaticNumberOfIterations is off, the number of iterations is
* given by MaximumNumberOfIterations. If it is on, we try to get
* the lowest good number (which may not be larger than
* MaximumNumberOfIterations ) */
itkSetMacro(AutomaticNumberOfIterations, bool);
itkGetConstMacro(AutomaticNumberOfIterations, bool);
itkBooleanMacro(AutomaticNumberOfIterations);
/** If ComputeInverse is on, the filter will compute the exponential
* of the opposite (minus) of the input vector field. The output displacement
* fields computed with ComputeInverse set to on and off respectively
* therefore represent spatial transformations that are inverses of
* each other. */
itkSetMacro(ComputeInverse, bool);
itkGetConstMacro(ComputeInverse, bool);
itkBooleanMacro(ComputeInverse);
/** Image dimension. */
itkStaticConstMacro(ImageDimension, unsigned int,
TInputImage::ImageDimension);
itkStaticConstMacro(OutputImageDimension, unsigned int,
TInputImage::ImageDimension);
itkStaticConstMacro(PixelDimension, unsigned int,
InputPixelType::Dimension);
itkStaticConstMacro(OutputPixelDimension, unsigned int,
OutputPixelType::Dimension);
#ifdef ITK_USE_CONCEPT_CHECKING
// Begin concept checking
itkConceptMacro( OutputHasNumericTraitsCheck,
( Concept::HasNumericTraits< typename OutputPixelType::ValueType > ) );
itkConceptMacro( SameDimensionCheck1,
( Concept::SameDimension< ImageDimension, OutputImageDimension > ) );
itkConceptMacro( SameDimensionCheck2,
( Concept::SameDimension< ImageDimension, PixelDimension > ) );
itkConceptMacro( SameDimensionCheck3,
( Concept::SameDimension< ImageDimension, OutputPixelDimension > ) );
// End concept checking
#endif
protected:
ExponentialDisplacementFieldImageFilter();
virtual ~ExponentialDisplacementFieldImageFilter() ITK_OVERRIDE {}
void PrintSelf(std::ostream & os, Indent indent) const ITK_OVERRIDE;
/**
* GenerateData()
*/
void GenerateData() ITK_OVERRIDE;
typedef typename InputImageType::RegionType RegionType;
typedef DivideImageFilter<
InputImageType,
itk::Image<InputPixelRealValueType, ImageDimension>,
OutputImageType > DivideByConstantType;
typedef CastImageFilter<
InputImageType, OutputImageType > CasterType;
typedef WarpVectorImageFilter<
OutputImageType,
OutputImageType, OutputImageType > VectorWarperType;
typedef VectorLinearInterpolateNearestNeighborExtrapolateImageFunction<
OutputImageType, double > FieldInterpolatorType;
typedef AddImageFilter<
OutputImageType, OutputImageType, OutputImageType > AdderType;
typedef typename DivideByConstantType::Pointer DivideByConstantPointer;
typedef typename CasterType::Pointer CasterPointer;
typedef typename VectorWarperType::Pointer VectorWarperPointer;
typedef typename FieldInterpolatorType::Pointer FieldInterpolatorPointer;
typedef typename FieldInterpolatorType::OutputType FieldInterpolatorOutputType;
typedef typename AdderType::Pointer AdderPointer;
private:
ITK_DISALLOW_COPY_AND_ASSIGN(ExponentialDisplacementFieldImageFilter);
bool m_AutomaticNumberOfIterations;
unsigned int m_MaximumNumberOfIterations;
bool m_ComputeInverse;
DivideByConstantPointer m_Divider;
CasterPointer m_Caster;
VectorWarperPointer m_Warper;
AdderPointer m_Adder;
};
} // end namespace itk
#ifndef ITK_MANUAL_INSTANTIATION
#include "itkExponentialDisplacementFieldImageFilter.hxx"
#endif
#endif
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