#include <itkMaskedFFTNormalizedCorrelationImageFilter.h>

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

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

Detailed Description

template<typename TInputImage, typename TOutputImage, typename TMaskImage = TInputImage>
class itk::MaskedFFTNormalizedCorrelationImageFilter< TInputImage, TOutputImage, TMaskImage >

Calculate masked normalized cross correlation using FFTs.

This filter calculates the masked normalized cross correlation (NCC) of two images under masks using FFTs instead of spatial correlation. It is much faster than spatial correlation for reasonably large structuring elements. This filter is not equivalent to simply masking the images first and then correlating them; the latter approach yields incorrect results because the zeros in the images still affect the metric in the correlation process. This filter implements the masked NCC correctly so that the masked-out regions are completely ignored. The fundamental difference is described in detail in the references below. If the masks are set to images of all ones, the result of this filter is the same as standard NCC.

Inputs: Two images are required as inputs, fixedImage and movingImage, and two are optional, fixedMask and movingMask. In the context of correlation, inputs are often defined as: "image" and "template". In this filter, the fixedImage plays the role of the image, and the movingImage plays the role of the template. However, this filter is capable of correlating any two images and is not restricted to small movingImages (templates). In the fixedMask and movingMask, non-zero positive values indicate locations of useful information in the corresponding image, whereas zero and negative values indicate locations that should be masked out (ignored). Internally, the masks are converted to have values of only 0 and 1. For each optional mask that is not set, the filter internally creates an image of ones, which is equivalent to not masking the image. Thus, if both masks are not set, the result will be equivalent to unmasked NCC. For example, if only a mask for the fixed image is needed, the movingMask can either not be set or can be set to an image of ones.

Optional parameters: The RequiredNumberOfOverlappingPixels enables the user to specify the minimum number of voxels of the two masks that must overlap; any location in the correlation map that results from fewer than this number of voxels will be set to zero. Larger values zero-out pixels on a larger border around the correlation image. Thus, larger values remove less stable computations but also limit the capture range. If RequiredNumberOfOverlappingPixels is set to 0, the default, no zeroing will take place.

The RequiredFractionOfOverlappingPixels enables the user to specify a fraction of the maximum number of overlapping pixels that need to overlap; any location in the correlation map that results from fewer than the product of this fraction and the internally computed maximum number of overlapping pixels will be set to zero. The value ranges between 0.0 and 1.0. This is very useful when the user does does not know beforehand the maximum number of pixels of the masks that will overlap. For example, when the masks have strange shapes, it is difficult to predict how the correlation of the masks will interact and what the maximum overlap will be. It is also useful when the mask shapes or sizes change because it is relative to the internally computed maximum of the overlap. Larger values zero-out pixels on a larger border around the correlation image. Thus, larger values remove less stable computations but also limit the capture range. Experiments have shown that a value between 0.1 and 0.6 works well for images with significant overlap and between 0.05 and 0.1 for images with little overlap (such as in stitching applications). If RequiredFractionOfOverlappingPixels is set to 0, the default, no zeroing will take place.

The user can either specify RequiredNumberOfOverlappingPixels or RequiredFractionOfOverlappingPixels (or both or none). Internally, the number of required pixels resulting from both of these methods is calculated and the one that gives the largest number of pixels is chosen. Since these both default to 0, if a user only sets one, the other is ignored.

Image size: fixedImage and movingImage need not be the same size, but fixedMask must be the same size as fixedImage, and movingMask must be the same size as movingImage. Furthermore, whereas some algorithms require that the "template" be smaller than the "image" because of errors in the regions where the two are not fully overlapping, this filter has no such restriction.

Image spacing: Since the computations are done in the pixel domain, all input images must have the same spacing.

Outputs; The output is an image of RealPixelType that is the masked NCC of the two images and its values range from -1.0 to 1.0. The size of this NCC image is, by definition, size(fixedImage) + size(movingImage) - 1.

Example filter usage:

using FilterType = itk::MaskedFFTNormalizedCorrelationImageFilter< ShortImageType, DoubleImageType >;
FilterType::Pointer filter = FilterType::New();
filter->SetFixedImage( fixedImage );
filter->SetMovingImage( movingImage );
filter->SetFixedImageMask( fixedMask );
filter->SetMovingImageMask( movingMask );
filter->SetRequiredNumberOfOverlappingPixels(20);
filter->Update();

Warning: The pixel type of the output image must be of real type (float or double). ConceptChecking is used to enforce the output pixel type. You will get a compilation error if the pixel type of the output image is not float or double.

References: 1) D. Padfield. "Masked object registration in the Fourier domain." Transactions on Image Processing. 2) D. Padfield. "Masked FFT registration". In Proc. Computer Vision and Pattern Recognition, 2010.

Author: : Dirk Padfield, GE Global Research, padfield@research.ge.com

Definition at line 140 of file itkMaskedFFTNormalizedCorrelationImageFilter.h.

Public Types
using	ConstPointer = SmartPointer< const Self >

using	FFTImagePointer = typename FFTImageType::Pointer

using	FFTImageType = Image< std::complex< RealPixelType >, ImageDimension >

using	InputImageConstPointer = typename InputImageType::ConstPointer

using	InputImagePointer = typename InputImageType::Pointer

using	InputImageType = TInputImage

using	InputRegionType = typename InputImageType::RegionType

using	InputSizeType = typename InputImageType::SizeType

using	MaskImagePointer = typename MaskImageType::Pointer

using	MaskImageType = TMaskImage

using	OutputImagePointer = typename OutputImageType::Pointer

using	OutputImageType = TOutputImage

using	OutputPixelType = typename OutputImageType::PixelType

using	Pointer = SmartPointer< Self >

using	RealImagePointer = typename RealImageType::Pointer

using	RealImageType = Image< RealPixelType, ImageDimension >

using	RealIndexType = typename RealImageType::IndexType

using	RealPixelType = OutputPixelType

using	RealPointType = typename RealImageType::PointType

using	RealRegionType = typename RealImageType::RegionType

using	RealSizeType = typename RealImageType::SizeType

using	Self = MaskedFFTNormalizedCorrelationImageFilter

using	SizeValueType = itk::SizeValueType

using	Superclass = ImageToImageFilter< TInputImage, TOutputImage >

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

using	InputImageConstPointer = typename InputImageType::ConstPointer

using	InputImagePixelType = typename InputImageType::PixelType

using	InputImagePointer = typename InputImageType::Pointer

using	InputImageRegionType = typename InputImageType::RegionType

using	InputImageType = TInputImage

using	OutputImagePixelType = typename Superclass::OutputImagePixelType

using	OutputImageRegionType = typename Superclass::OutputImageRegionType

using	Pointer = SmartPointer< Self >

using	Self = ImageToImageFilter

using	Superclass = ImageSource< TOutputImage >

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

using	DataObjectIdentifierType = Superclass::DataObjectIdentifierType

using	DataObjectPointer = DataObject::Pointer

using	DataObjectPointerArraySizeType = Superclass::DataObjectPointerArraySizeType

using	OutputImagePixelType = typename OutputImageType::PixelType

using	OutputImagePointer = typename OutputImageType::Pointer

using	OutputImageRegionType = typename OutputImageType::RegionType

using	OutputImageType = TOutputImage

using	Pointer = SmartPointer< Self >

using	Self = ImageSource

using	Superclass = ProcessObject

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

using	DataObjectIdentifierType = DataObject::DataObjectIdentifierType

using	DataObjectPointer = DataObject::Pointer

using	DataObjectPointerArray = std::vector< DataObjectPointer >

using	DataObjectPointerArraySizeType = DataObjectPointerArray::size_type

using	MultiThreaderType = MultiThreaderBase

using	NameArray = std::vector< DataObjectIdentifierType >

using	Pointer = SmartPointer< Self >

using	Self = ProcessObject

using	Superclass = Object

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

using	Pointer = SmartPointer< Self >

using	Self = Object

using	Superclass = LightObject

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

using	Pointer = SmartPointer< Self >

using	Self = LightObject

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

virtual SizeValueType	GetMaximumNumberOfOverlappingPixels ()

virtual const char *	GetNameOfClass () const


virtual void	SetFixedImage (const InputImageType *input)

virtual const InputImageType *	GetFixedImage () const


virtual void	SetMovingImage (const InputImageType *input)

virtual const InputImageType *	GetMovingImage () const


virtual void	SetFixedImageMask (const MaskImageType *input)

virtual const MaskImageType *	GetFixedImageMask () const


virtual void	SetMovingImageMask (const MaskImageType *input)

virtual const MaskImageType *	GetMovingImageMask () const


virtual void	SetRequiredNumberOfOverlappingPixels (SizeValueType _arg)

virtual SizeValueType	GetRequiredNumberOfOverlappingPixels ()


virtual RealPixelType	GetRequiredFractionOfOverlappingPixels ()

virtual void	SetRequiredFractionOfOverlappingPixels (RealPixelType _arg)

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

const InputImageType *	GetInput (unsigned int idx) const

void	PopBackInput () override

void	PopFrontInput () override

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)

OutputImageType *	GetOutput ()

const OutputImageType *	GetOutput () const

virtual void	GraftOutput (DataObject *output)

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

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

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

ProcessObject::DataObjectPointer	MakeOutput (const ProcessObject::DataObjectIdentifierType &) override

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

virtual void	AbortGenerateDataOn ()

virtual const bool &	GetAbortGenerateData () const

DataObjectPointerArray	GetIndexedInputs ()

DataObjectPointerArray	GetIndexedOutputs ()

NameArray	GetInputNames () const

DataObjectPointerArray	GetInputs ()

MultiThreaderType *	GetMultiThreader () const

DataObjectPointerArraySizeType	GetNumberOfIndexedInputs () const

DataObjectPointerArraySizeType	GetNumberOfIndexedOutputs () const

DataObjectPointerArraySizeType	GetNumberOfInputs () const

DataObjectPointerArraySizeType	GetNumberOfOutputs () const

virtual DataObjectPointerArraySizeType	GetNumberOfValidRequiredInputs () const

NameArray	GetOutputNames () const

DataObjectPointerArray	GetOutputs ()

virtual const float &	GetProgress () const

NameArray	GetRequiredInputNames () const

bool	HasInput (const DataObjectIdentifierType &key) const

bool	HasOutput (const DataObjectIdentifierType &key) const

virtual void	PrepareOutputs ()

virtual void	PropagateRequestedRegion (DataObject *output)

virtual void	ResetPipeline ()

virtual void	SetAbortGenerateData (bool _arg)

void	SetMultiThreader (MultiThreaderType *threader)

virtual void	Update ()

virtual void	UpdateLargestPossibleRegion ()

virtual void	UpdateOutputData (DataObject *output)

virtual void	UpdateOutputInformation ()

void	UpdateProgress (float progress)

virtual void	SetReleaseDataFlag (bool flag)

virtual bool	GetReleaseDataFlag () const

void	ReleaseDataFlagOn ()

void	ReleaseDataFlagOff ()

virtual void	SetReleaseDataBeforeUpdateFlag (bool _arg)

virtual const bool &	GetReleaseDataBeforeUpdateFlag () const

virtual void	ReleaseDataBeforeUpdateFlagOn ()

virtual void	ReleaseDataBeforeUpdateFlagOff ()

virtual void	SetNumberOfWorkUnits (ThreadIdType _arg)

virtual const ThreadIdType &	GetNumberOfWorkUnits () const

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 ()

const MetaDataDictionary &	GetMetaDataDictionary () 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

void	Register () const override

void	RemoveAllObservers ()

void	RemoveObserver (unsigned long tag)

void	SetDebug (bool debugFlag) const

void	SetReferenceCount (int) override

void	UnRegister () const noexceptoverride

void	SetMetaDataDictionary (const MetaDataDictionary &rhs)

void	SetMetaDataDictionary (MetaDataDictionary &&rrhs)

virtual void	SetObjectName (std::string _arg)

virtual const std::string &	GetObjectName () 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 Member Functions inherited from itk::Object
static bool	GetGlobalWarningDisplay ()

static void	GlobalWarningDisplayOff ()

static void	GlobalWarningDisplayOn ()

static Pointer	New ()

static void	SetGlobalWarningDisplay (bool flag)

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

static Pointer	New ()

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

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

static constexpr unsigned int	OutputImageDimension = TOutputImage::ImageDimension

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

Protected Member Functions
template<typename LocalInputImageType , typename LocalOutputImageType >
LocalOutputImageType::Pointer	CalculateForwardFFT (LocalInputImageType *inputImage, InputSizeType &FFTImageSize)

template<typename LocalInputImageType , typename LocalOutputImageType >
LocalOutputImageType::Pointer	CalculateInverseFFT (LocalInputImageType *inputImage, RealSizeType &combinedImageSize)

template<typename LocalInputImageType >
double	CalculatePrecisionTolerance (LocalInputImageType *inputImage)

template<typename LocalInputImageType >
LocalInputImageType::Pointer	ElementPositive (LocalInputImageType *inputImage)

template<typename LocalInputImageType , typename LocalOutputImageType >
LocalOutputImageType::Pointer	ElementProduct (LocalInputImageType inputImage1, LocalInputImageType inputImage2)

template<typename LocalInputImageType >
LocalInputImageType::Pointer	ElementQuotient (LocalInputImageType inputImage1, LocalInputImageType inputImage2)

template<typename LocalInputImageType , typename LocalOutputImageType >
LocalOutputImageType::Pointer	ElementRound (LocalInputImageType *inputImage)

template<typename LocalInputImageType >
LocalInputImageType::Pointer	ElementSubtraction (LocalInputImageType inputImage1, LocalInputImageType inputImage2)

void	EnlargeOutputRequestedRegion (DataObject *output) override

int	FactorizeNumber (int n)

int	FindClosestValidDimension (int n)

void	GenerateData () override

void	GenerateInputRequestedRegion () override

void	GenerateOutputInformation () override

	MaskedFFTNormalizedCorrelationImageFilter ()

TInputImage::Pointer	PreProcessImage (const InputImageType inputImage, const MaskImageType inputMask)

TMaskImage::Pointer	PreProcessMask (const InputImageType inputImage, const MaskImageType inputMask)

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

template<typename LocalInputImageType >
LocalInputImageType::Pointer	RotateImage (LocalInputImageType *inputImage)

void	VerifyInputInformation () ITKv5_CONST override

	~MaskedFFTNormalizedCorrelationImageFilter () override=default

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)

	ImageToImageFilter ()

	~ImageToImageFilter () override

void	PushBackInput (const DataObject *input) override

void	PushFrontInput (const DataObject *input) override

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

virtual void	AllocateOutputs ()

virtual void	BeforeThreadedGenerateData ()

void	ClassicMultiThread (ThreadFunctionType callbackFunction)

virtual const ImageRegionSplitterBase *	GetImageRegionSplitter () const

	ImageSource ()

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

	~ImageSource () override=default

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

virtual void	DynamicThreadedGenerateData (const OutputImageRegionType &outputRegionForThread)

virtual bool	GetDynamicMultiThreading () const

virtual void	SetDynamicMultiThreading (bool _arg)

virtual void	DynamicMultiThreadingOn ()

virtual void	DynamicMultiThreadingOff ()

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

void	AddOptionalInputName (const DataObjectIdentifierType &)

void	AddOptionalInputName (const DataObjectIdentifierType &, DataObjectPointerArraySizeType idx)

virtual void	AddOutput (DataObject *output)

bool	AddRequiredInputName (const DataObjectIdentifierType &)

bool	AddRequiredInputName (const DataObjectIdentifierType &, DataObjectPointerArraySizeType idx)

virtual void	CacheInputReleaseDataFlags ()

virtual void	GenerateOutputRequestedRegion (DataObject *output)

DataObject *	GetInput (const DataObjectIdentifierType &key)

const DataObject *	GetInput (const DataObjectIdentifierType &key) const

virtual const DataObjectPointerArraySizeType &	GetNumberOfRequiredInputs () const

virtual const DataObjectPointerArraySizeType &	GetNumberOfRequiredOutputs () const

bool	IsIndexedInputName (const DataObjectIdentifierType &) const

bool	IsIndexedOutputName (const DataObjectIdentifierType &) const

bool	IsRequiredInputName (const DataObjectIdentifierType &) const

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	SetNumberOfRequiredInputs (DataObjectPointerArraySizeType)

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 () ITKv5_CONST

	~ProcessObject () override

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 () 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

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

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

virtual void	SetTimeStamp (const TimeStamp &time)

	~Object () override

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 Attributes
float	m_AccumulatedProgress

SizeValueType	m_MaximumNumberOfOverlappingPixels

RealPixelType	m_RequiredFractionOfOverlappingPixels

SizeValueType	m_RequiredNumberOfOverlappingPixels

const unsigned int	m_TotalForwardAndInverseFFTs {12}

Additional Inherited Members
Protected Types inherited from itk::ImageToImageFilter< TInputImage, TOutputImage >
using	InputToOutputRegionCopierType = ImageToImageFilterDetail::ImageRegionCopier< Self::OutputImageDimension, Self::InputImageDimension >

using	OutputToInputRegionCopierType = ImageToImageFilterDetail::ImageRegionCopier< Self::InputImageDimension, Self::OutputImageDimension >

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

static ITK_THREAD_RETURN_FUNCTION_CALL_CONVENTION	ThreaderCallback (void *arg)

Protected Attributes inherited from itk::ImageSource< TOutputImage >
bool	m_DynamicMultiThreading

Protected Attributes inherited from itk::ProcessObject
TimeStamp	m_OutputInformationMTime

bool	m_Updating

Protected Attributes inherited from itk::LightObject
std::atomic< int >	m_ReferenceCount