SimpleITK  2.1.0.dev86
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

using PixelIDTypeList = BasicPixelIDTypeList

using Self = MaskedFFTNormalizedCorrelationImageFilter

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, const Image &fixedImageMask, const Image &movingImageMask)

std::string GetName () const

float GetRequiredFractionOfOverlappingPixels () const

uint64_t GetRequiredNumberOfOverlappingPixels () const

MaskedFFTNormalizedCorrelationImageFilter ()

SelfSetRequiredFractionOfOverlappingPixels (float RequiredFractionOfOverlappingPixels)

SelfSetRequiredNumberOfOverlappingPixels (uint64_t RequiredNumberOfOverlappingPixels)

std::string ToString () const

virtual ~MaskedFFTNormalizedCorrelationImageFilter ()

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, 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

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

float 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::ProcessObjectGetActiveProcess ()

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

NonCopyableoperator= (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<class TImageType >
static Image CastITKToImage (TImageType *img)

static const itk::EventObjectGetITKEventObject (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:

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.

See also
itk::simple::MaskedFFTNormalizedCorrelation for the procedural interface
itk::MaskedFFTNormalizedCorrelationImageFilter for the Doxygen on the original ITK class.

Definition at line 83 of file sitkMaskedFFTNormalizedCorrelationImageFilter.h.

## ◆ MemberFunctionType

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

Setup for member function dispatching

Definition at line 133 of file sitkMaskedFFTNormalizedCorrelationImageFilter.h.

## ◆ PixelIDTypeList

Define the pixels types supported by this filter

Definition at line 95 of file sitkMaskedFFTNormalizedCorrelationImageFilter.h.

## ◆ ~MaskedFFTNormalizedCorrelationImageFilter()

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

Destructor

## ◆ MaskedFFTNormalizedCorrelationImageFilter()

 itk::simple::MaskedFFTNormalizedCorrelationImageFilter::MaskedFFTNormalizedCorrelationImageFilter ( )

Default Constructor that takes no arguments and initializes default parameters

## ◆ Execute()

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

Execute the filter on the input image

## ◆ ExecuteInternal()

template<class TImageType >
 Image itk::simple::MaskedFFTNormalizedCorrelationImageFilter::ExecuteInternal ( const Image * fixedImage, const Image * movingImage, const Image * fixedImageMask, const Image * movingImageMask )
private

## ◆ GetName()

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

Name of this class

Implements itk::simple::ProcessObject.

Definition at line 119 of file sitkMaskedFFTNormalizedCorrelationImageFilter.h.

## ◆ GetRequiredFractionOfOverlappingPixels()

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

Set and get the required fraction of overlapping pixels

Definition at line 116 of file sitkMaskedFFTNormalizedCorrelationImageFilter.h.

## ◆ GetRequiredNumberOfOverlappingPixels()

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

Set and get the required number of overlapping pixels

Definition at line 106 of file sitkMaskedFFTNormalizedCorrelationImageFilter.h.

## ◆ SetRequiredFractionOfOverlappingPixels()

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

Set and get the required fraction of overlapping pixels

Definition at line 111 of file sitkMaskedFFTNormalizedCorrelationImageFilter.h.

## ◆ SetRequiredNumberOfOverlappingPixels()

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

Set and get the required number of overlapping pixels

Definition at line 101 of file sitkMaskedFFTNormalizedCorrelationImageFilter.h.

## ◆ ToString()

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

Print ourselves out

Reimplemented from itk::simple::ProcessObject.

## ◆ detail::MemberFunctionAddressor< MemberFunctionType >

 friend struct detail::MemberFunctionAddressor< MemberFunctionType >
friend

## ◆ m_MemberFactory

 std::unique_ptr > itk::simple::MaskedFFTNormalizedCorrelationImageFilter::m_MemberFactory
private

## ◆ m_RequiredFractionOfOverlappingPixels

 float itk::simple::MaskedFFTNormalizedCorrelationImageFilter::m_RequiredFractionOfOverlappingPixels {0.0}
private

## ◆ m_RequiredNumberOfOverlappingPixels

 uint64_t itk::simple::MaskedFFTNormalizedCorrelationImageFilter::m_RequiredNumberOfOverlappingPixels {0u}
private

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