itk::simple::MaskedFFTNormalizedCorrelationImageFilter Class Reference

Calculate masked normalized cross correlation using FFTs. More...

#include <sitkMaskedFFTNormalizedCorrelationImageFilter.h>

Inheritance diagram for itk::simple::MaskedFFTNormalizedCorrelationImageFilter:

Collaboration diagram for itk::simple::MaskedFFTNormalizedCorrelationImageFilter:

Public Types
typedef BasicPixelIDTypeList	PixelIDTypeList
typedef MaskedFFTNormalizedCorrelationImageFilter	Self
Public Types inherited from itk::simple::ImageFilter< 0 >
typedef ImageFilter	Self
Public Types inherited from itk::simple::ProcessObject
typedef ProcessObject	Self

Public Member Functions
Image	Execute (const Image &fixedImage, const Image &movingImage, const Image &fixedImageMask, const Image &movingImageMask)
Image	Execute (const Image &fixedImage, const Image &movingImage, const Image &fixedImageMask, const Image &movingImageMask, uint64_t requiredNumberOfOverlappingPixels, float requiredFractionOfOverlappingPixels)
std::string	GetName () const
float	GetRequiredFractionOfOverlappingPixels () const
uint64_t	GetRequiredNumberOfOverlappingPixels () const
	MaskedFFTNormalizedCorrelationImageFilter ()
Self &	SetRequiredFractionOfOverlappingPixels (float RequiredFractionOfOverlappingPixels)
Self &	SetRequiredNumberOfOverlappingPixels (uint64_t RequiredNumberOfOverlappingPixels)
std::string	ToString () const
virtual	~MaskedFFTNormalizedCorrelationImageFilter ()
Public Member Functions inherited from itk::simple::ImageFilter< 0 >
	ImageFilter ()
virtual	~ImageFilter ()=0
Public Member Functions inherited from itk::simple::ProcessObject
virtual void	Abort ()
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

Private Types
typedef Image(Self::*	MemberFunctionType) (const Image *fixedImage, const Image *movingImage, const Image *fixedImageMask, const Image *movingImageMask)

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

Private Attributes
nsstd::auto_ptr< detail::MemberFunctionFactory< MemberFunctionType > >	m_MemberFactory
float	m_RequiredFractionOfOverlappingPixels
uint64_t	m_RequiredNumberOfOverlappingPixels

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 void	SetGlobalDefaultNumberOfThreads (unsigned int n)
static unsigned int	GetGlobalDefaultNumberOfThreads ()
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...
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) SITK_NOEXCEPT
virtual void	PreUpdate (itk::ProcessObject *p)
virtual void	RemoveITKObserver (EventCommand &e)
Protected Member Functions inherited from itk::simple::NonCopyable
	NonCopyable ()
Static Protected Member Functions inherited from itk::simple::ImageFilter< 0 >
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 TImageType >
static Image	CastITKToImage (TImageType *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)
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 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:

typedef itk::MaskedFFTNormalizedCorrelationImageFilter< ShortImageType, DoubleImageType > FilterType;

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, padfi.nosp@m.eld@.nosp@m.resea.nosp@m.rch..nosp@m.ge.co.nosp@m.m

See also

itk::simple::MaskedFFTNormalizedCorrelation for the procedural interface

itk::MaskedFFTNormalizedCorrelationImageFilter for the Doxygen on the original ITK class.

Definition at line 81 of file sitkMaskedFFTNormalizedCorrelationImageFilter.h.

Member Typedef Documentation

typedef Image(Self::* itk::simple::MaskedFFTNormalizedCorrelationImageFilter::MemberFunctionType) (const Image *fixedImage, const Image *movingImage, const Image *fixedImageMask, const Image *movingImageMask)

private

Setup for member function dispatching

Definition at line 134 of file sitkMaskedFFTNormalizedCorrelationImageFilter.h.

typedef BasicPixelIDTypeList itk::simple::MaskedFFTNormalizedCorrelationImageFilter::PixelIDTypeList

Define the pixels types supported by this filter

Definition at line 93 of file sitkMaskedFFTNormalizedCorrelationImageFilter.h.

typedef MaskedFFTNormalizedCorrelationImageFilter itk::simple::MaskedFFTNormalizedCorrelationImageFilter::Self

Definition at line 83 of file sitkMaskedFFTNormalizedCorrelationImageFilter.h.

Constructor & Destructor Documentation

virtual itk::simple::MaskedFFTNormalizedCorrelationImageFilter::~MaskedFFTNormalizedCorrelationImageFilter ( )

virtual

Destructor

itk::simple::MaskedFFTNormalizedCorrelationImageFilter::MaskedFFTNormalizedCorrelationImageFilter

(

)

Default Constructor that takes no arguments and initializes default parameters

Member Function Documentation

Image itk::simple::MaskedFFTNormalizedCorrelationImageFilter::Execute	(	const Image &	fixedImage,
		const Image &	movingImage,
		const Image &	fixedImageMask,
		const Image &	movingImageMask
	)

Execute the filter on the input image

Image itk::simple::MaskedFFTNormalizedCorrelationImageFilter::Execute	(	const Image &	fixedImage,
		const Image &	movingImage,
		const Image &	fixedImageMask,
		const Image &	movingImageMask,
		uint64_t	requiredNumberOfOverlappingPixels,
		float	requiredFractionOfOverlappingPixels
	)

Execute the filter on the input image with the given parameters

template<class TImageType >

Image itk::simple::MaskedFFTNormalizedCorrelationImageFilter::ExecuteInternal ( const Image *  fixedImage, const Image *  movingImage, const Image *  fixedImageMask, const Image *  movingImageMask  )

private

std::string itk::simple::MaskedFFTNormalizedCorrelationImageFilter::GetName ( ) const

inlinevirtual

Name of this class

Implements itk::simple::ProcessObject.

Definition at line 117 of file sitkMaskedFFTNormalizedCorrelationImageFilter.h.

float itk::simple::MaskedFFTNormalizedCorrelationImageFilter::GetRequiredFractionOfOverlappingPixels ( ) const

inline

Set and get the required fraction of overlapping pixels

Definition at line 115 of file sitkMaskedFFTNormalizedCorrelationImageFilter.h.

uint64_t itk::simple::MaskedFFTNormalizedCorrelationImageFilter::GetRequiredNumberOfOverlappingPixels ( ) const

inline

Set and get the required number of overlapping pixels

Definition at line 105 of file sitkMaskedFFTNormalizedCorrelationImageFilter.h.

Self& itk::simple::MaskedFFTNormalizedCorrelationImageFilter::SetRequiredFractionOfOverlappingPixels ( float  RequiredFractionOfOverlappingPixels )

inline

Set and get the required fraction of overlapping pixels

Definition at line 110 of file sitkMaskedFFTNormalizedCorrelationImageFilter.h.

Self& itk::simple::MaskedFFTNormalizedCorrelationImageFilter::SetRequiredNumberOfOverlappingPixels ( uint64_t  RequiredNumberOfOverlappingPixels )

inline

Set and get the required number of overlapping pixels

Definition at line 100 of file sitkMaskedFFTNormalizedCorrelationImageFilter.h.

std::string itk::simple::MaskedFFTNormalizedCorrelationImageFilter::ToString ( ) const

virtual

Print ourselves out

Reimplemented from itk::simple::ProcessObject.

Friends And Related Function Documentation

friend struct detail::MemberFunctionAddressor< MemberFunctionType >

friend

Definition at line 138 of file sitkMaskedFFTNormalizedCorrelationImageFilter.h.

Member Data Documentation

nsstd::auto_ptr<detail::MemberFunctionFactory<MemberFunctionType> > itk::simple::MaskedFFTNormalizedCorrelationImageFilter::m_MemberFactory

private

Definition at line 140 of file sitkMaskedFFTNormalizedCorrelationImageFilter.h.

float itk::simple::MaskedFFTNormalizedCorrelationImageFilter::m_RequiredFractionOfOverlappingPixels

private

Definition at line 144 of file sitkMaskedFFTNormalizedCorrelationImageFilter.h.

uint64_t itk::simple::MaskedFFTNormalizedCorrelationImageFilter::m_RequiredNumberOfOverlappingPixels

private

Definition at line 143 of file sitkMaskedFFTNormalizedCorrelationImageFilter.h.

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The documentation for this class was generated from the following file:

• sitkMaskedFFTNormalizedCorrelationImageFilter.h