#include <itkVectorGradientMagnitudeImageFilter.h>

Inheritance diagram for itk::VectorGradientMagnitudeImageFilter< TInputImage, TRealType, TOutputImage >:

Collaboration diagram for itk::VectorGradientMagnitudeImageFilter< TInputImage, TRealType, TOutputImage >:

Detailed Description

template<typename TInputImage, typename TRealType = float, typename TOutputImage = Image< TRealType, TInputImage::ImageDimension >>
class itk::VectorGradientMagnitudeImageFilter< TInputImage, TRealType, TOutputImage >

Computes a scalar, gradient magnitude image from a multiple channel (pixels are vectors) input.

Overview: This filter has two calculation modes. The first (default) mode calculates gradient magnitude as the difference between the largest two eigenvalues in a principle component analysis of the partial derivatives [1]. The gradient is then based on the direction of maximal change, and is a characterization of how "elongated" the point-spread of the analysis is found to be.

The second, more heuristic, calculation mode finds gradient magnitude as the square-root of the sum of the * individual weighted vector component derivative sums squared. That is, * $\mathbf{magnitude} = \left( \sum_{i=0}^n \sum_{j=0}^m \frac{\delta * \phi_j}{\delta \mathbf{x}_{i}}^2 \right)^{\frac{1}{2}}$ , where $\phi_j$ * is the $j^{\mathbf{th}}$ channel of vector image $\phi$ of dimension $n$ . * Weighting terms are applied to each vector component.

The second mode is computationally much faster than the first and has the advantage that it is automatically multi-threaded (some vnl functions used in the first mode are not thread-safe). The first mode, however, tends to give intuitively better results with less (or no) parameter tuning.

Template Parameters (Input and Output): This filter has one required template parameter which defines the input image type. The pixel type of the input image is assumed to be a vector (e.g., itk::Vector, itk::RGBPixel, itk::FixedArray). The scalar type of the vector components must be castable to floating point. Instantiating with an image of RGBPixel<unsigned short>, for example, is allowed, but the filter will convert it to an image of Vector<float,3> for processing.

The second template parameter, TRealType, can be optionally specified to define the scalar numerical type used in calculations. This is the component type of the output image, which will be of itk::Vector<TRealType, N>, where N is the number of channels in the multiple component input image. The default type of TRealType is float. For extra precision, you may safely change this parameter to double.

The third template parameter is the output image type. The third parameter will be automatically constructed from the first and second parameters, so it is not necessary (or advisable) to set this parameter explicitly. Given an M-channel input image with dimensionality N, and a numerical type specified as TRealType, the output image will be of type itk::Image<itk::Vector<TRealType, M>, N>.

Filter Parameters: The methods Set/GetUsePrincipleComponents and SetUsePrincipleComponentsOn/Off determine controls the calculation mode that is used.

The method SetUseImageSpacingOn will cause derivatives in the image to be scaled (inversely) with the pixel size of the input image, effectively taking derivatives in world coordinates (versus isotropic image space). SetUseImageSpacingOff turns this functionality off. Default is UseImageSpacingOn. The parameter UseImageSpacing can be set directly with the method SetUseImageSpacing(bool).

Weights can be applied to the derivatives directly using the SetDerivativeWeights method. Note that if UseImageSpacing is set to TRUE (ON), then these weights will be overridden by weights derived from the image spacing when the filter is updated. The argument to this method is a C array of TRealValue type.

Weights can be applied to each vector component of the image when the component derivative values are summed during computation. Specify these weights using the SetComponentWeights method. The argument to this method is a C array of TRealValue type.

Constraints: The filter requires an image with at least two dimensions and a vector length of at least 2. The theory supports extension to scalar images, but the implementation of the itk vector classes do not

The template parameter TRealType must be floating point (float or double) or a user-defined "real" numerical type with arithmetic operations defined sufficient to compute derivatives.

Performance: This filter will automatically multithread if run with SetUsePrincipleComponents=Off or on 3D data in UsePrincipleComponents=On mode. Unfortunately the ND eigen solver used is not thread safe (a special 3D solver is), so it cannot multithread for data other than 3D in UsePrincipleComponents=On mode.

References

[1] G. Sapiro and D. Ringach, "Anisotropic Diffusion of Multivalued Images with Application to Color Filtering," IEEE Transactions on Image Processing, Vol 5, No. 11 pp. 1582-1586, 1996

See Also: Image; Neighborhood; NeighborhoodOperator; NeighborhoodIterator

Definition at line 139 of file itkVectorGradientMagnitudeImageFilter.h.

Public Types
typedef ConstNeighborhoodIterator < RealVectorImageType >	ConstNeighborhoodIteratorType

typedef SmartPointer< const Self >	ConstPointer

typedef InputImageType::Pointer	InputImagePointer

typedef TInputImage	InputImageType

typedef TInputImage::PixelType	InputPixelType

typedef OutputImageType::Pointer	OutputImagePointer

typedef Superclass::OutputImageRegionType	OutputImageRegionType

typedef TOutputImage	OutputImageType

typedef TOutputImage::PixelType	OutputPixelType

typedef SmartPointer< Self >	Pointer

typedef ConstNeighborhoodIteratorType::RadiusType	RadiusType

typedef TRealType	RealType

typedef Image< RealVectorType, TInputImage::ImageDimension >	RealVectorImageType

typedef Vector< TRealType, InputPixelType::Dimension >	RealVectorType

typedef VectorGradientMagnitudeImageFilter	Self

typedef ImageToImageFilter < TInputImage, TOutputImage >	Superclass

typedef FixedArray< TRealType, VectorDimension >	WeightsType

Public Types inherited from itk::ImageToImageFilter< TInputImage, TOutputImage >
typedef SmartPointer< const Self >	ConstPointer

typedef InputImageType::ConstPointer	InputImageConstPointer

typedef InputImageType::PixelType	InputImagePixelType

typedef InputImageType::Pointer	InputImagePointer

typedef InputImageType::RegionType	InputImageRegionType

typedef TInputImage	InputImageType

typedef Superclass::OutputImagePixelType	OutputImagePixelType

typedef Superclass::OutputImageRegionType	OutputImageRegionType

typedef SmartPointer< Self >	Pointer

typedef ImageToImageFilter	Self

typedef ImageSource< TOutputImage >	Superclass

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

typedef Superclass::DataObjectIdentifierType	DataObjectIdentifierType

typedef DataObject::Pointer	DataObjectPointer

typedef Superclass::DataObjectPointerArraySizeType	DataObjectPointerArraySizeType

typedef OutputImageType::PixelType	OutputImagePixelType

typedef OutputImageType::Pointer	OutputImagePointer

typedef OutputImageType::RegionType	OutputImageRegionType

typedef TOutputImage	OutputImageType

typedef SmartPointer< Self >	Pointer

typedef ImageSource	Self

typedef ProcessObject	Superclass

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

typedef DataObject::DataObjectIdentifierType	DataObjectIdentifierType

typedef DataObject::Pointer	DataObjectPointer

typedef std::vector < DataObjectPointer >	DataObjectPointerArray

typedef DataObjectPointerArray::size_type	DataObjectPointerArraySizeType

typedef std::vector < DataObjectIdentifierType >	NameArray

typedef SmartPointer< Self >	Pointer

typedef ProcessObject	Self

typedef Object	Superclass

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

typedef SmartPointer< Self >	Pointer

typedef Object	Self

typedef LightObject	Superclass

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

typedef SmartPointer< Self >	Pointer

typedef LightObject	Self

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

virtual void	GenerateInputRequestedRegion () throw ( InvalidRequestedRegionError )

virtual const char *	GetNameOfClass () const

virtual bool	GetUseImageSpacing () const

void	SetUseImageSpacing (bool)

void	SetUseImageSpacingOff ()

void	SetUseImageSpacingOn ()

void	SetUsePrincipleComponentsOff ()

	typedef (Concept::HasNumericTraits< typename InputPixelType::ValueType >) InputHasNumericTraitsCheck

	typedef (Concept::HasNumericTraits< RealType >) RealTypeHasNumericTraitsCheck


virtual void	SetDerivativeWeights (WeightsType _arg)

virtual const WeightsType &	GetDerivativeWeights ()


virtual void	SetComponentWeights (WeightsType _arg)

virtual const WeightsType &	GetComponentWeights ()


virtual const RadiusType &	GetNeighborhoodRadius ()

virtual void	SetNeighborhoodRadius (RadiusType _arg)


virtual void	SetUsePrincipleComponents (bool _arg)

virtual bool	GetUsePrincipleComponents () const

void	SetUsePrincipleComponentsOn ()

Public Member Functions inherited from itk::ImageToImageFilter< TInputImage, TOutputImage >
virtual double	GetCoordinateTolerance ()

const InputImageType *	GetInput (void) const

const InputImageType *	GetInput (unsigned int idx) const

virtual void	PopBackInput ()

virtual void	PopFrontInput ()

virtual void	PushBackInput (const InputImageType *image)

virtual void	PushFrontInput (const InputImageType *image)

virtual void	SetCoordinateTolerance (double _arg)

virtual void	SetInput (const InputImageType *image)

virtual void	SetInput (unsigned int, const TInputImage *image)

virtual void	SetDirectionTolerance (double _arg)

virtual double	GetDirectionTolerance ()

Public Member Functions inherited from itk::ImageSource< TOutputImage >
OutputImageType *	GetOutput (unsigned int idx)

virtual void	GraftNthOutput (unsigned int idx, DataObject *output)

virtual void	GraftOutput (DataObject *output)

virtual void	GraftOutput (const DataObjectIdentifierType &key, DataObject *output)

OutputImageType *	GetOutput (void)

const OutputImageType *	GetOutput (void) const

virtual ProcessObject::DataObjectPointer	MakeOutput (ProcessObject::DataObjectPointerArraySizeType idx)

Public Member Functions inherited from itk::ProcessObject
virtual void	AbortGenerateDataOff ()

virtual void	AbortGenerateDataOn ()

virtual void	EnlargeOutputRequestedRegion (DataObject *)

virtual const bool &	GetAbortGenerateData ()

NameArray	GetInputNames () const

MultiThreader *	GetMultiThreader () const

DataObjectPointerArraySizeType	GetNumberOfIndexedInputs () const

DataObjectPointerArraySizeType	GetNumberOfInputs () const

DataObjectPointerArraySizeType	GetNumberOfOutputs () const

virtual DataObjectPointerArraySizeType	GetNumberOfValidRequiredInputs () const

NameArray	GetOutputNames () const

virtual const float &	GetProgress ()

NameArray	GetRequiredInputNames () const

bool	HasInput (const DataObjectIdentifierType &key) const

bool	HasOutput (const DataObjectIdentifierType &key) const

virtual DataObjectPointer	MakeOutput (const DataObjectIdentifierType &)

virtual void	PrepareOutputs ()

virtual void	PropagateRequestedRegion (DataObject *output)

virtual void	ResetPipeline ()

virtual void	SetAbortGenerateData (bool _arg)

virtual void	SetProgress (float _arg)

virtual void	Update ()

virtual void	UpdateLargestPossibleRegion ()

virtual void	UpdateOutputData (DataObject *output)

virtual void	UpdateOutputInformation ()

void	UpdateProgress (float amount)

DataObjectPointerArray	GetInputs ()

DataObjectPointerArray	GetOutputs ()

DataObjectPointerArray	GetIndexedInputs ()

DataObjectPointerArray	GetIndexedOutputs ()

DataObjectPointerArraySizeType	GetNumberOfIndexedOutputs () const

virtual void	SetReleaseDataFlag (bool flag)

virtual bool	GetReleaseDataFlag () const

void	ReleaseDataFlagOn ()

void	ReleaseDataFlagOff ()

virtual void	SetReleaseDataBeforeUpdateFlag (bool _arg)

virtual const bool &	GetReleaseDataBeforeUpdateFlag ()

virtual void	ReleaseDataBeforeUpdateFlagOn ()

virtual void	ReleaseDataBeforeUpdateFlagOff ()

virtual void	SetNumberOfThreads (ThreadIdType _arg)

virtual const ThreadIdType &	GetNumberOfThreads ()

Public Member Functions inherited from itk::Object
unsigned long	AddObserver (const EventObject &event, Command *)

unsigned long	AddObserver (const EventObject &event, Command *) const

virtual void	DebugOff () const

virtual void	DebugOn () const

Command *	GetCommand (unsigned long tag)

bool	GetDebug () const

MetaDataDictionary &	GetMetaDataDictionary (void)

const MetaDataDictionary &	GetMetaDataDictionary (void) const

virtual ModifiedTimeType	GetMTime () const

virtual const TimeStamp &	GetTimeStamp () const

bool	HasObserver (const EventObject &event) const

void	InvokeEvent (const EventObject &)

void	InvokeEvent (const EventObject &) const

virtual void	Modified () const

virtual void	Register () const

void	RemoveAllObservers ()

void	RemoveObserver (unsigned long tag)

void	SetDebug (bool debugFlag) const

void	SetMetaDataDictionary (const MetaDataDictionary &rhs)

virtual void	SetReferenceCount (int)

virtual void	UnRegister () const

Public Member Functions inherited from itk::LightObject
virtual void	Delete ()

virtual int	GetReferenceCount () const

	itkCloneMacro (Self)

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

Static Public Member Functions
static int	CubicSolver (double , double )

static Pointer	New ()

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

static const unsigned int	VectorDimension = InputPixelType::Dimension

Static Public Attributes inherited from itk::ImageToImageFilter< TInputImage, TOutputImage >
static const unsigned int	InputImageDimension = TInputImage::ImageDimension

static const unsigned int	OutputImageDimension = TOutputImage::ImageDimension

Static Public Attributes inherited from itk::ImageSource< TOutputImage >
static const unsigned int	OutputImageDimension = TOutputImage::ImageDimension

Protected Types
typedef InputImageType::Superclass	ImageBaseType

Protected Types inherited from itk::ImageToImageFilter< TInputImage, TOutputImage >
typedef ImageToImageFilterDetail::ImageRegionCopier < itkGetStaticConstMacro(OutputImageDimension), itkGetStaticConstMacro(InputImageDimension) >	InputToOutputRegionCopierType

typedef ImageToImageFilterDetail::ImageRegionCopier < itkGetStaticConstMacro(InputImageDimension), itkGetStaticConstMacro(OutputImageDimension) >	OutputToInputRegionCopierType

Protected Member Functions
void	BeforeThreadedGenerateData ()

TRealType	EvaluateAtNeighborhood (const ConstNeighborhoodIteratorType &it) const

TRealType	EvaluateAtNeighborhood3D (const ConstNeighborhoodIteratorType &it) const

virtual const ImageBaseType *	GetRealValuedInputImage ()

TRealType	NonPCEvaluateAtNeighborhood (const ConstNeighborhoodIteratorType &it) const

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

void	ThreadedGenerateData (const OutputImageRegionType &outputRegionForThread, ThreadIdType threadId)

	VectorGradientMagnitudeImageFilter ()

virtual	~VectorGradientMagnitudeImageFilter ()

Protected Member Functions inherited from itk::ImageToImageFilter< TInputImage, TOutputImage >
virtual void	CallCopyInputRegionToOutputRegion (OutputImageRegionType &destRegion, const InputImageRegionType &srcRegion)

virtual void	CallCopyOutputRegionToInputRegion (InputImageRegionType &destRegion, const OutputImageRegionType &srcRegion)

virtual void	VerifyInputInformation ()

void	PushBackInput (const DataObject *input)

void	PushFrontInput (const DataObject *input)

	ImageToImageFilter ()

	~ImageToImageFilter ()

Protected Member Functions inherited from itk::ImageSource< TOutputImage >
virtual void	AfterThreadedGenerateData ()

virtual void	AllocateOutputs ()

virtual void	GenerateData ()

	ImageSource ()

virtual unsigned int	SplitRequestedRegion (unsigned int i, unsigned int num, OutputImageRegionType &splitRegion)

virtual	~ImageSource ()

Protected Member Functions inherited from itk::ProcessObject
virtual void	AddInput (DataObject *input)

virtual void	AddOutput (DataObject *output)

bool	AddRequiredInputName (const DataObjectIdentifierType &)

virtual void	CacheInputReleaseDataFlags ()

virtual void	GenerateOutputInformation ()

virtual void	GenerateOutputRequestedRegion (DataObject *output)

virtual const DataObjectPointerArraySizeType &	GetNumberOfRequiredOutputs ()

bool	IsIndexedInputName (const DataObjectIdentifierType &) const

bool	IsIndexedOutputName (const DataObjectIdentifierType &) const

bool	IsRequiredInputName (const DataObjectIdentifierType &) const

	itkLegacyMacro (virtual void RemoveInput(DataObject *input))

	itkLegacyMacro (virtual void RemoveOutput(DataObject *output))

	itkLegacyMacro (void SetNumberOfInputs(DataObjectPointerArraySizeType num))

	itkLegacyMacro (void SetNumberOfOutputs(DataObjectPointerArraySizeType num))

DataObjectPointerArraySizeType	MakeIndexFromInputName (const DataObjectIdentifierType &name) const

DataObjectPointerArraySizeType	MakeIndexFromOutputName (const DataObjectIdentifierType &name) const

DataObjectIdentifierType	MakeNameFromInputIndex (DataObjectPointerArraySizeType idx) const

DataObjectIdentifierType	MakeNameFromOutputIndex (DataObjectPointerArraySizeType idx) const

	ProcessObject ()

virtual void	PropagateResetPipeline ()

virtual void	ReleaseInputs ()

virtual void	RemoveInput (const DataObjectIdentifierType &key)

virtual void	RemoveInput (DataObjectPointerArraySizeType)

virtual void	RemoveOutput (const DataObjectIdentifierType &key)

virtual void	RemoveOutput (DataObjectPointerArraySizeType idx)

bool	RemoveRequiredInputName (const DataObjectIdentifierType &)

virtual void	RestoreInputReleaseDataFlags ()

virtual void	SetInput (const DataObjectIdentifierType &key, DataObject *input)

virtual void	SetNthInput (DataObjectPointerArraySizeType num, DataObject *input)

virtual void	SetNthOutput (DataObjectPointerArraySizeType num, DataObject *output)

void	SetNumberOfIndexedInputs (DataObjectPointerArraySizeType num)

void	SetNumberOfIndexedOutputs (DataObjectPointerArraySizeType num)

virtual void	SetNumberOfRequiredOutputs (DataObjectPointerArraySizeType _arg)

virtual void	SetOutput (const DataObjectIdentifierType &key, DataObject *output)

virtual void	SetPrimaryInput (DataObject *input)

virtual void	SetPrimaryOutput (DataObject *output)

void	SetRequiredInputNames (const NameArray &)

virtual void	VerifyPreconditions ()

	~ProcessObject ()

DataObject *	GetInput (const DataObjectIdentifierType &key)

const DataObject *	GetInput (const DataObjectIdentifierType &key) const

DataObject *	GetInput (DataObjectPointerArraySizeType)

const DataObject *	GetInput (DataObjectPointerArraySizeType idx) const

DataObject *	GetPrimaryInput ()

const DataObject *	GetPrimaryInput () const

virtual void	SetPrimaryInputName (const DataObjectIdentifierType &key)

virtual const char *	GetPrimaryInputName () const

DataObject *	GetOutput (const DataObjectIdentifierType &key)

const DataObject *	GetOutput (const DataObjectIdentifierType &key) const

virtual void	SetPrimaryOutputName (const DataObjectIdentifierType &key)

virtual const char *	GetPrimaryOutputName () const

DataObject *	GetOutput (DataObjectPointerArraySizeType idx)

const DataObject *	GetOutput (DataObjectPointerArraySizeType idx) const

DataObject *	GetPrimaryOutput ()

const DataObject *	GetPrimaryOutput () const

virtual void	SetNumberOfRequiredInputs (DataObjectPointerArraySizeType)

virtual const DataObjectPointerArraySizeType &	GetNumberOfRequiredInputs ()

Protected Member Functions inherited from itk::Object
	Object ()

bool	PrintObservers (std::ostream &os, Indent indent) const

virtual void	SetTimeStamp (const TimeStamp &time)

virtual	~Object ()

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
WeightsType	m_ComponentWeights

WeightsType	m_DerivativeWeights

WeightsType	m_SqrtComponentWeights

Private Member Functions
void	operator= (const Self &)

	VectorGradientMagnitudeImageFilter (const Self &)

Private Attributes
RadiusType	m_NeighborhoodRadius

ImageBaseType::ConstPointer	m_RealValuedInputImage

ThreadIdType	m_RequestedNumberOfThreads

bool	m_UseImageSpacing

bool	m_UsePrincipleComponents

Additional Inherited Members
Static Protected Member Functions inherited from itk::ImageSource< TOutputImage >
static ITK_THREAD_RETURN_TYPE	ThreaderCallback (void *arg)