Detailed Description

template<typename TInputImage, typename TOutputImage>
class itk::STAPLEImageFilter< TInputImage, TOutputImage >

The STAPLE filter implements the Simultaneous Truth and Performance Level Estimation algorithm for generating ground truth volumes from a set of binary expert segmentations.

The STAPLE algorithm treats segmentation as a pixelwise classification, which leads to an averaging scheme that accounts for systematic biases in the behavior of experts in order to generate a fuzzy ground truth volume and simultaneous accuracy assessment of each expert. The ground truth volumes produced by this filter are floating point volumes of values between zero and one that indicate probability of each pixel being in the object targeted by the segmentation.

The STAPLE algorithm is described in

S. Warfield, K. Zou, W. Wells, "Validation of image segmentation and expert quality with an expectation-maximization algorithm" in MICCAI 2002: Fifth International Conference on Medical Image Computing and Computer-Assisted Intervention, Springer-Verlag, Heidelberg, Germany, 2002, pp. 298-306

INPUTS: Input volumes to the STAPLE filter must be binary segmentations of an image, that is, there must be a single foreground value that represents positively classified pixels (pixels that are considered to belong inside the segmentation). Any number of background pixel values may be present in the input images. You can, for example, input volumes with many different labels as long as the structure you are interested in creating ground truth for is consistently labeled among all input volumes. Pixel type of the input volumes does not matter. Specify the label value for positively classified pixels using SetForegroundValue. All other labels will be considered to be negatively classified pixels (background).

Input volumes must all contain the same size RequestedRegions.

OUTPUTS: The STAPLE filter produces a single output volume with a range of floating point values from zero to one. IT IS VERY IMPORTANT TO INSTANTIATE THIS FILTER WITH A FLOATING POINT OUTPUT TYPE (floats or doubles). You may threshold the output above some probability threshold if you wish to produce a binary ground truth.

PARAMETERS: The STAPLE algorithm requires a number of inputs. You may specify any number of input volumes using the SetInput(i, p_i) method, where i ranges from zero to N-1, N is the total number of input segmentations, and p_i is the SmartPointer to the i-th segmentation.

The SetConfidenceWeight parameter is a modifier for the prior probability that any pixel would be classified as inside the target object. This implementation of the STAPLE algorithm automatically calculates prior positive classification probability as the average fraction of the image volume filled by the target object in each input segmentation. The ConfidenceWeight parameter allows for scaling the of this default prior probability: if g_t is the prior probability that a pixel would be classified inside the target object, then g_t is set to g_t * ConfidenceWeight before iterating on the solution. In general ConfidenceWeight should be left to the default of 1.0.

You must provide a foreground value using SetForegroundValue that the STAPLE algorithm will use to identify positively classified pixels in the the input images. All other values in the image will be treated as background values. For example, if your input segmentations consist of 1's everywhere inside the segmented region, then use SetForegroundValue(1).

The STAPLE algorithm is an iterative E-M algorithm and will converge on a solution after some number of iterations that cannot be known a priori. After updating the filter, the total elapsed iterations taken to converge on the solution can be queried through GetElapsedIterations(). You may also specify a MaximumNumberOfIterations, after which the algorithm will stop iterating regardless of whether or not it has converged. This implementation of the STAPLE algorithm will find the solution to within seven digits of precision unless it is stopped early.

Once updated, the Sensitivity (true positive fraction, q) and Specificity (true negative fraction, q) for each expert input volume can be queried using GetSensitivity(i) and GetSpecificity(i), where i is the i-th input volume.

REQUIRED PARAMETERS: The only required parameters for this filter are the ForegroundValue and the input volumes. All other parameters may be safely left to their default values. Please see the paper cited above for more information on the STAPLE algorithm and its parameters. A proper understanding of the algorithm is important for interpreting the results that it produces.

EVENTS: This filter invokes IterationEvent() at each iteration of the E-M algorithm. Setting the AbortGenerateData() flag will cause the algorithm to halt after the current iteration and produce results just as if it had converged. The algorithm makes no attempt to report its progress since the number of iterations needed cannot be known in advance.

Definition at line 121 of file itkSTAPLEImageFilter.h.

Public Types
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 NumericTraits < InputPixelType >::RealType	RealType

typedef STAPLEImageFilter	Self

typedef ImageToImageFilter < TInputImage, TOutputImage >	Superclass

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 unsigned int	GetElapsedIterations () const

virtual const char *	GetNameOfClass () const

const std::vector< double > &	GetSensitivity () const

const std::vector< double > &	GetSpecificity () const

	typedef (Concept::HasNumericTraits< InputPixelType >) InputHasNumericTraitsCheck


virtual void	SetForegroundValue (InputPixelType _arg)

virtual InputPixelType	GetForegroundValue () const


double	GetSensitivity (unsigned int i)


double	GetSpecificity (unsigned int i)


virtual void	SetMaximumIterations (unsigned int _arg)

virtual unsigned int	GetMaximumIterations () const


virtual void	SetConfidenceWeight (double _arg)

virtual double	GetConfidenceWeight () const

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 Pointer	New ()

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

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

	STAPLEImageFilter ()

virtual	~STAPLEImageFilter ()

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 ()

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	BeforeThreadedGenerateData ()

	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)

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 ()

Private Member Functions
void	operator= (const Self &)

	STAPLEImageFilter (const Self &)

Private Attributes
double	m_ConfidenceWeight

unsigned int	m_ElapsedIterations

InputPixelType	m_ForegroundValue

unsigned int	m_MaximumIterations

std::vector< double >	m_Sensitivity

std::vector< double >	m_Specificity

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 ITK_THREAD_RETURN_TYPE	ThreaderCallback (void *arg)

Protected Attributes inherited from itk::ProcessObject
TimeStamp	m_OutputInformationMTime

bool	m_Updating