#include <itkFiniteDifferenceFunction.h>

Inheritance diagram for itk::FiniteDifferenceFunction< TImageType >:

Collaboration diagram for itk::FiniteDifferenceFunction< TImageType >:

Detailed Description

template<class TImageType>
class itk::FiniteDifferenceFunction< TImageType >

This class is a component object of the finite difference solver hierarchy (see FiniteDifferenceImageFilter). It defines a generic interface for a function object that computes a single scalar value from a neighborhood of values. Examples of the application of this class are the various flavors of AnisotropicDiffusionFunction and LevelSetFunction objects.

These functions calculate the incremental change at a pixel in the solution image from one iteration of the Partial Differential Equation (PDE) solver to the next.

: Subclasses of FiniteDifferenceImageFilter (solvers) call the ComputeUpdate() method of this class to compute $\Delta u^n_{\mathbf{i}}$ at each $\mathbf{i}$ in . Because the size of the time step for each iteration of the p.d.e. solution depends on the particular calculations done, this function object is also responsible for computing that time step (see ComputeGlobalTimeStep() ).

How to use this class: FiniteDifferenceFunction must be subclassed to add functionality for ComputeUpdate, ComputeGlobalTimeStep, and Get/ReleaseGlobalDataPointer.

A note on thread safety.: The ComputeUpdate() methods of this filter are declared as const to enforce thread-safety during execution of FiniteDifferenceImageFilter solver algorithms. The InitializeIteration() method is intended to provide a safe way to modify the state of the object between threaded calculations of solvers.

Todo:: Possibly subclass this object from Function. Stumbling blocks here are the specialized api of FiniteDifferenceFunction.

Definition at line 66 of file itkFiniteDifferenceFunction.h.

Public Types
typedef SmartPointer< const Self >	ConstPointer

typedef ZeroFluxNeumannBoundaryCondition < ImageType >	DefaultBoundaryConditionType

typedef Vector< float, itkGetStaticConstMacro(ImageDimension) >	FloatOffsetType

typedef TImageType	ImageType

typedef Vector< PixelRealType, itkGetStaticConstMacro(ImageDimension) >	NeighborhoodScalesType

typedef ConstNeighborhoodIterator < TImageType, DefaultBoundaryConditionType >	NeighborhoodType

typedef double	PixelRealType

typedef ImageType::PixelType	PixelType

typedef SmartPointer< Self >	Pointer

typedef ConstNeighborhoodIterator < TImageType >::RadiusType	RadiusType

typedef FiniteDifferenceFunction	Self

typedef LightObject	Superclass

typedef double	TimeStepType

Public Types inherited from itk::LightObject
typedef SmartPointer< const Self >	ConstPointer

typedef SmartPointer< Self >	Pointer

typedef LightObject	Self

Public Member Functions
virtual TimeStepType	ComputeGlobalTimeStep (void *GlobalData) const =0

const NeighborhoodScalesType	ComputeNeighborhoodScales () const

virtual PixelType	ComputeUpdate (const NeighborhoodType &neighborhood, void *globalData, const FloatOffsetType &offset=FloatOffsetType(0.0))=0

virtual void *	GetGlobalDataPointer () const =0

virtual const char *	GetNameOfClass () const

const RadiusType &	GetRadius () const

void	GetScaleCoefficients (PixelRealType vals[ImageDimension]) const

virtual void	InitializeIteration ()

virtual void	ReleaseGlobalDataPointer (void *GlobalData) const =0

void	SetRadius (const RadiusType &r)

void	SetScaleCoefficients (PixelRealType vals[ImageDimension])

Public Member Functions inherited from itk::LightObject
virtual Pointer	CreateAnother () const

virtual void	Delete ()

virtual int	GetReferenceCount () const

	itkCloneMacro (Self)

void	Print (std::ostream &os, Indent indent=0) const

virtual void	Register () const

virtual void	SetReferenceCount (int)

virtual void	UnRegister () const

Static Public Attributes
static const unsigned int	ImageDimension = ImageType::ImageDimension

Protected Member Functions
	FiniteDifferenceFunction ()

void	PrintSelf (std::ostream &os, Indent indent) const

	~FiniteDifferenceFunction ()

Protected Member Functions inherited from itk::LightObject
virtual LightObject::Pointer	InternalClone () const

	LightObject ()

virtual void	PrintHeader (std::ostream &os, Indent indent) const

virtual void	PrintTrailer (std::ostream &os, Indent indent) const

virtual	~LightObject ()

Protected Attributes
RadiusType	m_Radius

PixelRealType	m_ScaleCoefficients [ImageDimension]

Protected Attributes inherited from itk::LightObject
InternalReferenceCountType	m_ReferenceCount

SimpleFastMutexLock	m_ReferenceCountLock

Private Member Functions
	FiniteDifferenceFunction (const Self &)

void	operator= (const Self &)

Additional Inherited Members
Static Public Member Functions inherited from itk::LightObject
static void	BreakOnError ()

static Pointer	New ()

Protected Types inherited from itk::LightObject
typedef int	InternalReferenceCountType

Member Typedef Documentation

template<class TImageType>

typedef SmartPointer< const Self > itk::FiniteDifferenceFunction< TImageType >::ConstPointer

Definition at line 74 of file itkFiniteDifferenceFunction.h.

template<class TImageType>

typedef ZeroFluxNeumannBoundaryCondition< ImageType > itk::FiniteDifferenceFunction< TImageType >::DefaultBoundaryConditionType

The default boundary condition for finite difference functions that is used unless overridden in the Evaluate() method.

Definition at line 93 of file itkFiniteDifferenceFunction.h.

template<class TImageType>

typedef Vector< float, itkGetStaticConstMacro(ImageDimension) > itk::FiniteDifferenceFunction< TImageType >::FloatOffsetType

A floating point offset from an image grid location. Used for interpolation among grid values in a neighborhood.

Definition at line 108 of file itkFiniteDifferenceFunction.h.

template<class TImageType>

typedef TImageType itk::FiniteDifferenceFunction< TImageType >::ImageType

Extract some parameters from the image type

Definition at line 77 of file itkFiniteDifferenceFunction.h.

template<class TImageType>

typedef Vector< PixelRealType, itkGetStaticConstMacro(ImageDimension) > itk::FiniteDifferenceFunction< TImageType >::NeighborhoodScalesType

The type of data structure that holds the scales with which the neighborhood is weighted to properly account for spacing and neighborhood radius.

Definition at line 104 of file itkFiniteDifferenceFunction.h.

template<class TImageType>

typedef ConstNeighborhoodIterator< TImageType, DefaultBoundaryConditionType > itk::FiniteDifferenceFunction< TImageType >::NeighborhoodType

The type of data structure that is passed to this function object to evaluate at a pixel that does not lie on a data set boundary.

Definition at line 100 of file itkFiniteDifferenceFunction.h.

template<class TImageType>

typedef double itk::FiniteDifferenceFunction< TImageType >::PixelRealType

Definition at line 82 of file itkFiniteDifferenceFunction.h.

template<class TImageType>

typedef ImageType::PixelType itk::FiniteDifferenceFunction< TImageType >::PixelType

Definition at line 81 of file itkFiniteDifferenceFunction.h.

template<class TImageType>

typedef SmartPointer< Self > itk::FiniteDifferenceFunction< TImageType >::Pointer

Definition at line 73 of file itkFiniteDifferenceFunction.h.

template<class TImageType>

typedef ConstNeighborhoodIterator< TImageType >::RadiusType itk::FiniteDifferenceFunction< TImageType >::RadiusType

Neighborhood radius type

Definition at line 96 of file itkFiniteDifferenceFunction.h.

template<class TImageType>

typedef FiniteDifferenceFunction itk::FiniteDifferenceFunction< TImageType >::Self

Standard class typedefs.

Definition at line 71 of file itkFiniteDifferenceFunction.h.

template<class TImageType>

typedef LightObject itk::FiniteDifferenceFunction< TImageType >::Superclass

Definition at line 72 of file itkFiniteDifferenceFunction.h.

template<class TImageType>

typedef double itk::FiniteDifferenceFunction< TImageType >::TimeStepType

Define the TimeStepType to always be double.

Definition at line 88 of file itkFiniteDifferenceFunction.h.

Constructor & Destructor Documentation

template<class TImageType>

itk::FiniteDifferenceFunction< TImageType >::FiniteDifferenceFunction ( )

protected

template<class TImageType>

itk::FiniteDifferenceFunction< TImageType >::~FiniteDifferenceFunction ( )

inlineprotected

Definition at line 188 of file itkFiniteDifferenceFunction.h.

template<class TImageType>

itk::FiniteDifferenceFunction< TImageType >::FiniteDifferenceFunction ( const Self & )

private

Member Function Documentation

template<class TImageType>

virtual TimeStepType itk::FiniteDifferenceFunction< TImageType >::ComputeGlobalTimeStep ( void * GlobalData ) const

pure virtual

Computes the time step for an update given a global data structure. The data used in the computation may take different forms depending on the nature of the equations. This global data cannot be kept in the instance of the equation object itself since the equation object must remain stateless for thread safety. The global data is therefore managed for each thread by the finite difference solver filters.

template<class TImageType>

const NeighborhoodScalesType itk::FiniteDifferenceFunction< TImageType >::ComputeNeighborhoodScales ( ) const

Compute the scales that weight the neighborhood during difference operations to properly account for spacing and neighborhood radius

template<class TImageType>

virtual PixelType itk::FiniteDifferenceFunction< TImageType >::ComputeUpdate	(	const NeighborhoodType &	neighborhood,
		void *	globalData,
		const FloatOffsetType &	offset = `FloatOffsetType(0.0)`
	)

pure virtual

This method is called by a finite difference solver image filter at each pixel that does not lie on a data set boundary. The width of the data set boundary is defined by the width of the neighborhood being evaluated.

The neighborhood argument is the neighborhood data. The globalData argument is a pointer to a data structure that holds values that need to be persistent across calls to this function, but cannot be stored in the function object itself for thread-safety reasons. Examples are values needed to compute the time-step for an iteration of the solver.

See Also: InitializeIteration; ComputeGlobalTimeStep

template<class TImageType>

virtual void* itk::FiniteDifferenceFunction< TImageType >::GetGlobalDataPointer ( ) const

pure virtual

Returns a pointer to a global data structure that is passed to this object from the solver at each calculation. The idea is that the solver holds the state of any global values needed to calculate the time step, while the equation object performs the actual calculations.

The global data should also be initialized in this method.

template<class TImageType>

virtual const char* itk::FiniteDifferenceFunction< TImageType >::GetNameOfClass ( ) const

virtual

Run-time type information (and related methods)

Reimplemented from itk::LightObject.

template<class TImageType>

const RadiusType& itk::FiniteDifferenceFunction< TImageType >::GetRadius ( ) const

Returns the radius of the neighborhood this FiniteDifferenceFunction needs to perform its calculations.

template<class TImageType>

void itk::FiniteDifferenceFunction< TImageType >::GetScaleCoefficients ( PixelRealType vals[ImageDimension] ) const

Returns the current scale coefficients.

template<class TImageType>

virtual void itk::FiniteDifferenceFunction< TImageType >::InitializeIteration ( )

inlinevirtual

This method allows the function to set its state before each iteration of the finite difference solver (image filter) that uses it. This is a thread-safe time to manipulate the object's state.

An example of how this can be used: the AnisotropicDiffusionFunction class of FiniteDifferenceFunction use this method to pre-calculate an average gradient magnitude across the entire image region. This value is set in the function object and used by the ComputeUpdate() methods that are called at each pixel as a constant.

Definition at line 119 of file itkFiniteDifferenceFunction.h.

template<class TImageType>

void itk::FiniteDifferenceFunction< TImageType >::operator= ( const Self & )

private

template<class TImageType>

void itk::FiniteDifferenceFunction< TImageType >::PrintSelf	(	std::ostream &	os,
		Indent	indent
	)		const

protectedvirtual

Methods invoked by Print() to print information about the object including superclasses. Typically not called by the user (use Print() instead) but used in the hierarchical print process to combine the output of several classes.

Reimplemented from itk::LightObject.

template<class TImageType>

virtual void itk::FiniteDifferenceFunction< TImageType >::ReleaseGlobalDataPointer ( void * GlobalData ) const

pure virtual

When the finite difference solver filter has finished using a global data pointer, it passes it to this method, which frees the memory.

The solver cannot free the memory because it does not know the type to which the pointer points.

template<class TImageType>

void itk::FiniteDifferenceFunction< TImageType >::SetRadius ( const RadiusType & r )

Sets the radius of the neighborhood this FiniteDifferenceFunction needs to perform its calculations.

template<class TImageType>

void itk::FiniteDifferenceFunction< TImageType >::SetScaleCoefficients ( PixelRealType vals[ImageDimension] )

Set the ScaleCoefficients for the difference operators. The defaults a 1.0. These can be set to take the image spacing into account.

Member Data Documentation

template<class TImageType>

const unsigned int itk::FiniteDifferenceFunction< TImageType >::ImageDimension = ImageType::ImageDimension

static

Save image dimension.

Definition at line 85 of file itkFiniteDifferenceFunction.h.

template<class TImageType>

RadiusType itk::FiniteDifferenceFunction< TImageType >::m_Radius

protected

Definition at line 192 of file itkFiniteDifferenceFunction.h.

template<class TImageType>

PixelRealType itk::FiniteDifferenceFunction< TImageType >::m_ScaleCoefficients[ImageDimension]

protected

Definition at line 193 of file itkFiniteDifferenceFunction.h.

The documentation for this class was generated from the following file:

itkFiniteDifferenceFunction.h

Detailed Description

template<class TImageType> class itk::FiniteDifferenceFunction< TImageType >

Public Types

Public Member Functions

Static Public Attributes

Protected Member Functions

Protected Attributes

Private Member Functions

Additional Inherited Members

Member Typedef Documentation

Constructor & Destructor Documentation

Member Function Documentation

Member Data Documentation

template<class TImageType>
class itk::FiniteDifferenceFunction< TImageType >