#include <itkN4BiasFieldCorrectionImageFilter.h>

Inheritance diagram for itk::N4BiasFieldCorrectionImageFilter< TInputImage, TMaskImage, TOutputImage >:

Collaboration diagram for itk::N4BiasFieldCorrectionImageFilter< TInputImage, TMaskImage, TOutputImage >:

Detailed Description

template<class TInputImage, class TMaskImage = Image<unsigned char, TInputImage::ImageDimension>, class TOutputImage = TInputImage>
class itk::N4BiasFieldCorrectionImageFilter< TInputImage, TMaskImage, TOutputImage >

Implementation of the N4 bias field correction algorithm.

The nonparametric nonuniform intensity normalization (N3) algorithm, as introduced by Sled et al. in 1998 is a method for correcting nonuniformity associated with MR images. The algorithm assumes a simple parametric model (Gaussian) for the bias field and does not require tissue class segmentation. In addition, there are only a couple of parameters to tune with the default values performing quite well. N3 has been publicly available as a set of perl scripts (http://www.bic.mni.mcgill.ca/ServicesSoftwareAdvancedImageProcessingTools/HomePage)

The N4 algorithm, encapsulated with this class, is a variation of the original N3 algorithm with the additional benefits of an improved B-spline fitting routine which allows for multiple resolutions to be used during the correction process. We also modify the iterative update component of algorithm such that the residual bias field is continually updated

Notes for the user:

Since much of the image manipulation is done in the log space of the intensities, input images with negative and small values (< 1) can produce poor results.
The original authors recommend performing the bias field correction on a downsampled version of the original image.
A binary mask or a weighted image can be supplied. If a binary mask is specified, those voxels in the input image which correspond to the voxels in the mask image with a value equal to m_MaskLabel, are used to estimate the bias field. If a confidence image is specified, the input voxels are weighted in the b-spline fitting routine according to the confidence voxel values.
The filter returns the corrected image. If the bias field is wanted, one can reconstruct it using the class itkBSplineControlPointImageFilter. See the IJ article and the test file for an example.
The 'Z' parameter in Sled's 1998 paper is the square root of the class variable 'm_WienerFilterNoise'.

The basic algorithm iterates between sharpening the intensity histogram of the corrected input image and spatially smoothing those results with a B-spline scalar field estimate of the bias field.

Author: Nicholas J. Tustison

Contributed by Nicholas J. Tustison, James C. Gee in the Insight Journal paper: http://hdl.handle.net/10380/3053

REFERENCE

J.G. Sled, A.P. Zijdenbos and A.C. Evans. "A Nonparametric Method for Automatic Correction of Intensity Nonuniformity in Data" IEEE Transactions on Medical Imaging, Vol 17, No 1. Feb 1998.

N.J. Tustison, B.B. Avants, P.A. Cook, Y. Zheng, A. Egan, P.A. Yushkevich, and J.C. Gee. "N4ITK: Improved N3 Bias Correction" IEEE Transactions on Medical Imaging, 29(6):1310-1320, June 2010.

Definition at line 93 of file itkN4BiasFieldCorrectionImageFilter.h.

Public Types
typedef BSplineFilterType::ArrayType	ArrayType

typedef BSplineFilterType::PointDataImageType	BiasFieldControlPointLatticeType

typedef BSplineScatteredDataPointSetToImageFilter < PointSetType, ScalarImageType >	BSplineFilterType

typedef SmartPointer< const Self >	ConstPointer

typedef TInputImage	InputImageType

typedef TMaskImage	MaskImageType

typedef MaskImageType::PixelType	MaskPixelType

typedef TOutputImage	OutputImageType

typedef SmartPointer< Self >	Pointer

typedef RealImageType::Pointer	RealImagePointer

typedef Image< RealType, ImageDimension >	RealImageType

typedef float	RealType

typedef N4BiasFieldCorrectionImageFilter	Self

typedef ImageToImageFilter < TInputImage, TOutputImage >	Superclass

typedef Array< unsigned int >	VariableSizeArrayType


typedef Vector< RealType, 1 >	ScalarType

typedef PointSet< ScalarType, itkGetStaticConstMacro(ImageDimension)>	PointSetType

typedef Image< ScalarType, itkGetStaticConstMacro(ImageDimension)>	ScalarImageType

typedef PointSetType::Pointer	PointSetPointer

typedef PointSetType::PointType	PointType

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 RealType	GetBiasFieldFullWidthAtHalfMaximum () const

const RealImageType *	GetConfidenceImage () const

virtual RealType	GetConvergenceThreshold () const

virtual RealType	GetCurrentConvergenceMeasurement () const

virtual unsigned int	GetCurrentLevel () const

virtual unsigned int	GetElapsedIterations () const

virtual BiasFieldControlPointLatticeType::Pointer	GetLogBiasFieldControlPointLattice () const

const MaskImageType *	GetMaskImage () const

virtual MaskPixelType	GetMaskLabel () const

virtual VariableSizeArrayType	GetMaximumNumberOfIterations () const

virtual const char *	GetNameOfClass () const

virtual ArrayType	GetNumberOfControlPoints () const

virtual ArrayType	GetNumberOfFittingLevels () const

virtual unsigned int	GetNumberOfHistogramBins () const

virtual unsigned int	GetSplineOrder () const

virtual RealType	GetWienerFilterNoise () const

virtual void	SetBiasFieldFullWidthAtHalfMaximum (RealType _arg)

virtual void	SetConvergenceThreshold (RealType _arg)

void	SetInput1 (const InputImageType *image)

virtual void	SetMaskLabel (MaskPixelType _arg)

virtual void	SetMaximumNumberOfIterations (VariableSizeArrayType _arg)

virtual void	SetNumberOfControlPoints (ArrayType _arg)

virtual void	SetNumberOfFittingLevels (ArrayType _arg)

void	SetNumberOfFittingLevels (unsigned int n)

virtual void	SetNumberOfHistogramBins (unsigned int _arg)

virtual void	SetSplineOrder (unsigned int _arg)

virtual void	SetWienerFilterNoise (RealType _arg)


void	SetMaskImage (const MaskImageType *mask)

void	SetInput2 (const MaskImageType *mask)


void	SetConfidenceImage (const RealImageType *image)

void	SetInput3 (const RealImageType *image)

Public Member Functions inherited from itk::ImageToImageFilter< TInputImage, TOutputImage >
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	SetInput (const InputImageType *image)

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

virtual void	SetCoordinateTolerance (double _arg)

virtual double	GetCoordinateTolerance () const

virtual void	SetDirectionTolerance (double _arg)

virtual double	GetDirectionTolerance () const

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 Pointer	New ()

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

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 Member Functions
void	GenerateData ()

	N4BiasFieldCorrectionImageFilter ()

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

	~N4BiasFieldCorrectionImageFilter ()

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	GenerateInputRequestedRegion ()

	ImageToImageFilter ()

virtual void	VerifyInputInformation ()

	~ImageToImageFilter ()

void	PushBackInput (const DataObject *input)

void	PushFrontInput (const DataObject *input)

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

virtual void	AllocateOutputs ()

virtual void	BeforeThreadedGenerateData ()

virtual const ImageRegionSplitterBase *	GetImageRegionSplitter (void) const

	ImageSource ()

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

virtual void	ThreadedGenerateData (const OutputImageRegionType &outputRegionForThread, ThreadIdType threadId)

virtual	~ImageSource ()

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

virtual void	AddOutput (DataObject *output)

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

	itkLegacyMacro (virtual void RemoveOutput(DataObject *output))

	itkLegacyMacro (void SetNumberOfOutputs(DataObjectPointerArraySizeType num))

	itkLegacyMacro (virtual void RemoveInput(DataObject *input))

	itkLegacyMacro (void SetNumberOfInputs(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)

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)

virtual void	VerifyPreconditions ()

	~ProcessObject ()

DataObject *	GetInput (const DataObjectIdentifierType &key)

const DataObject *	GetInput (const DataObjectIdentifierType &key) const

DataObject *	GetInput (DataObjectPointerArraySizeType idx)

const DataObject *	GetInput (DataObjectPointerArraySizeType idx) const

DataObject *	GetPrimaryInput ()

const DataObject *	GetPrimaryInput () const

virtual void	SetPrimaryInputName (const DataObjectIdentifierType &key)

virtual const char *	GetPrimaryInputName (void) const

virtual void	SetNumberOfRequiredInputs (DataObjectPointerArraySizeType)

virtual const DataObjectPointerArraySizeType &	GetNumberOfRequiredInputs ()

bool	AddRequiredInputName (const DataObjectIdentifierType &)

bool	AddRequiredInputName (const DataObjectIdentifierType &, DataObjectPointerArraySizeType idx)

bool	RemoveRequiredInputName (const DataObjectIdentifierType &)

bool	IsRequiredInputName (const DataObjectIdentifierType &) const

void	SetRequiredInputNames (const NameArray &)

DataObject *	GetOutput (const DataObjectIdentifierType &key)

const DataObject *	GetOutput (const DataObjectIdentifierType &key) const

virtual void	SetPrimaryOutputName (const DataObjectIdentifierType &key)

virtual const char *	GetPrimaryOutputName (void) const

DataObject *	GetOutput (DataObjectPointerArraySizeType idx)

const DataObject *	GetOutput (DataObjectPointerArraySizeType idx) const

DataObject *	GetPrimaryOutput ()

const DataObject *	GetPrimaryOutput () const

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 ()

Private Member Functions
RealType	CalculateConvergenceMeasurement (const RealImageType , const RealImageType ) const

	N4BiasFieldCorrectionImageFilter (const Self &)

void	operator= (const Self &)

RealImagePointer	SharpenImage (const RealImageType *) const

RealImagePointer	UpdateBiasFieldEstimate (RealImageType *)

Private Attributes
RealType	m_BiasFieldFullWidthAtHalfMaximum

RealType	m_ConvergenceThreshold

RealType	m_CurrentConvergenceMeasurement

unsigned int	m_CurrentLevel

unsigned int	m_ElapsedIterations

BiasFieldControlPointLatticeType::Pointer	m_LogBiasFieldControlPointLattice

MaskPixelType	m_MaskLabel

VariableSizeArrayType	m_MaximumNumberOfIterations

ArrayType	m_NumberOfControlPoints

ArrayType	m_NumberOfFittingLevels

unsigned int	m_NumberOfHistogramBins

unsigned int	m_SplineOrder

RealType	m_WienerFilterNoise

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

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

Static Protected Member Functions inherited from itk::ImageSource< TOutputImage >
static const ImageRegionSplitterBase *	GetGlobalDefaultSplitter ()

static ITK_THREAD_RETURN_TYPE	ThreaderCallback (void *arg)

Protected Attributes inherited from itk::ProcessObject
TimeStamp	m_OutputInformationMTime

bool	m_Updating