Calculate normalized cross correlation using FFTs. More...

#include <sitkFFTNormalizedCorrelationImageFilter.h>

Inheritance diagram for itk::simple::FFTNormalizedCorrelationImageFilter:

Collaboration diagram for itk::simple::FFTNormalizedCorrelationImageFilter:

Public Types
using	PixelIDTypeList = BasicPixelIDTypeList

using	Self = FFTNormalizedCorrelationImageFilter

Public Types inherited from itk::simple::ImageFilter
using	Self = ImageFilter

Public Types inherited from itk::simple::ProcessObject
using	Self = ProcessObject

Public Member Functions
Image	Execute (const Image &fixedImage, const Image &movingImage)

	FFTNormalizedCorrelationImageFilter ()

std::string	GetName () const

double	GetRequiredFractionOfOverlappingPixels () const

uint64_t	GetRequiredNumberOfOverlappingPixels () const

Self &	SetRequiredFractionOfOverlappingPixels (double RequiredFractionOfOverlappingPixels)

Self &	SetRequiredNumberOfOverlappingPixels (uint64_t RequiredNumberOfOverlappingPixels)

std::string	ToString () const

virtual	~FFTNormalizedCorrelationImageFilter ()

Public Member Functions inherited from itk::simple::ImageFilter
	ImageFilter ()

virtual	~ImageFilter ()=0

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

virtual int	AddCommand (itk::simple::EventEnum event, const std::function< void()> &func)
	Directly add a callback to observe an event. More...

virtual int	AddCommand (itk::simple::EventEnum event, itk::simple::Command &cmd)
	Add a Command Object to observer the event. More...

virtual float	GetProgress () const
	An Active Measurement of the progress of execution. More...

virtual bool	HasCommand (itk::simple::EventEnum event) const
	Query of this object has any registered commands for event. More...

	ProcessObject ()

virtual void	RemoveAllCommands ()
	Remove all registered commands. More...

virtual	~ProcessObject ()

virtual void	DebugOn ()

virtual void	DebugOff ()

virtual bool	GetDebug () const

virtual void	SetDebug (bool debugFlag)

virtual void	SetNumberOfThreads (unsigned int n)

virtual unsigned int	GetNumberOfThreads () const

virtual void	SetNumberOfWorkUnits (unsigned int n)

virtual unsigned int	GetNumberOfWorkUnits () const

Private Types
using	MemberFunctionType = Image(Self::)(const Image fixedImage, const Image *movingImage)

Private Member Functions
template<class TImageType >
Image	ExecuteInternal (const Image fixedImage, const Image movingImage)

Private Attributes
std::unique_ptr< detail::MemberFunctionFactory< MemberFunctionType > >	m_MemberFactory

double	m_RequiredFractionOfOverlappingPixels {0.0}

uint64_t	m_RequiredNumberOfOverlappingPixels {0u}

Friends
struct	detail::MemberFunctionAddressor< MemberFunctionType >

Additional Inherited Members
Static Public Member Functions inherited from itk::simple::ProcessObject
static bool	GetGlobalDefaultDebug ()

static void	GlobalDefaultDebugOff ()

static void	GlobalDefaultDebugOn ()

static void	SetGlobalDefaultDebug (bool debugFlag)

static void	GlobalWarningDisplayOn ()

static void	GlobalWarningDisplayOff ()

static void	SetGlobalWarningDisplay (bool flag)

static bool	GetGlobalWarningDisplay ()

static double	GetGlobalDefaultCoordinateTolerance ()
	Access the global tolerance to determine congruent spaces. More...

static void	SetGlobalDefaultCoordinateTolerance (double)
	Access the global tolerance to determine congruent spaces. More...

static double	GetGlobalDefaultDirectionTolerance ()
	Access the global tolerance to determine congruent spaces. More...

static void	SetGlobalDefaultDirectionTolerance (double)
	Access the global tolerance to determine congruent spaces. More...

static bool	SetGlobalDefaultThreader (const std::string &threader)
	Set/Get the default threader used for process objects. More...

static std::string	GetGlobalDefaultThreader ()
	Set/Get the default threader used for process objects. More...

static void	SetGlobalDefaultNumberOfThreads (unsigned int n)

static unsigned int	GetGlobalDefaultNumberOfThreads ()
	Set/Get the default threader used for process objects. More...

Protected Member Functions inherited from itk::simple::ImageFilter
void	CheckImageMatchingDimension (const Image &image1, const Image &image2, const std::string &image2Name)

void	CheckImageMatchingPixelType (const Image &image1, const Image &image2, const std::string &image2Name)

void	CheckImageMatchingSize (const Image &image1, const Image &image2, const std::string &image2Name)

Protected Member Functions inherited from itk::simple::ProcessObject
virtual unsigned long	AddITKObserver (const itk::EventObject &, itk::Command *)

virtual itk::ProcessObject *	GetActiveProcess ()

virtual void	OnActiveProcessDelete ()

virtual void	onCommandDelete (const itk::simple::Command *cmd) noexcept

virtual void	PreUpdate (itk::ProcessObject *p)

virtual void	RemoveITKObserver (EventCommand &e)

Protected Member Functions inherited from itk::simple::NonCopyable
	NonCopyable ()=default

	NonCopyable (const NonCopyable &)=delete

NonCopyable &	operator= (const NonCopyable &)=delete

Static Protected Member Functions inherited from itk::simple::ImageFilter
template<class TImageType >
static void	FixNonZeroIndex (TImageType *img)

Static Protected Member Functions inherited from itk::simple::ProcessObject
template<class TImageType >
static TImageType::ConstPointer	CastImageToITK (const Image &img)

template<class TPixelType , unsigned int VImageDimension, unsigned int VLength, template< typename, unsigned int > class TVector>
static Image	CastITKToImage (itk::Image< TVector< TPixelType, VLength >, VImageDimension > *img)

template<unsigned int VImageDimension, unsigned int VLength, template< unsigned int > class TVector>
static Image	CastITKToImage (itk::Image< TVector< VLength >, VImageDimension > *img)

template<class TImageType >
static Image	CastITKToImage (TImageType *img)

static const itk::EventObject &	GetITKEventObject (EventEnum e)

template<typename T >
static std::ostream &	ToStringHelper (std::ostream &os, const T &v)

static std::ostream &	ToStringHelper (std::ostream &os, const char &v)

static std::ostream &	ToStringHelper (std::ostream &os, const signed char &v)

static std::ostream &	ToStringHelper (std::ostream &os, const unsigned char &v)

Detailed Description

Calculate normalized cross correlation using FFTs.

This filter calculates the normalized cross correlation (NCC) of two images using FFTs instead of spatial correlation. It is much faster than spatial correlation for reasonably large structuring elements. This filter is a subclass of the more general MaskedFFTNormalizedCorrelationImageFilter and operates by essentially setting the masks in that algorithm to images of ones. As described in detail in the references below, there is no computational overhead to utilizing the more general masked algorithm because the FFTs of the images of ones are still necessary for the computations.

Inputs: Two images are required as inputs, fixedImage and movingImage. 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).

Optional parameters: The RequiredNumberOfOverlappingPixels enables the user to specify how many voxels of the two images 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.

Image size: fixedImage and movingImage need not be the same size. 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 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::FFTNormalizedCorrelationImageFilter< ShortImageType, DoubleImageType > ;
 
auto filter = FilterType::New ();
 
filter->SetFixedImage( fixedImage );
 
filter->SetMovingImage( movingImage );
 
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.