itk::simple::ContourExtractor2DImageFilter Class Reference

Computes a list of PolyLineParametricPath objects from the contours in a 2D image. More...

#include <sitkContourExtractor2DImageFilter.h>

Inheritance diagram for itk::simple::ContourExtractor2DImageFilter:

Collaboration diagram for itk::simple::ContourExtractor2DImageFilter:

Detailed Description

Computes a list of PolyLineParametricPath objects from the contours in a 2D image.

Uses the "marching squares" method to compute a the iso-valued contours of the input 2D image for a given intensity value. Multiple outputs may be produced because an image can have multiple contours at a given level, so it is advised to call GetNumberOfIndexedOutputs() and GetOutput(n) to retrieve all of the contours. The contour value to be extracted can be set with SetContourValue(). Image intensities will be linearly interpolated to provide sub-pixel resolution for the output contours.

The marching squares algorithm is a special case of the marching cubes algorithm [73]. A simple explanation is available here: http://users.polytech.unice.fr/~lingrand/MarchingCubes/algo.html

There is an ambiguous case in the marching squares algorithm: if a given 2x2-pixel square has two high-valued and two low-valued pixels, each pair diagonally adjacent. (Note that high-valued and low-valued are with respect to the contour value sought when LabelContours is false. When LabelContours is true, high-valued means the label being traced and low-valued means any other label.) In this case, the default behavior is that the low-valued pixels are connected into the same contour via an isthmus that separates the high-valued pixels into separate contours. To reverse this, call VertexConnectHighPixelsOn(). Note that when LabelContours is true, the default behavior will leave all four pixels in separate contours. In this case, VertexConnectHighPixels equal to true can instead create contours that are crossing barbells.

Outputs are not guaranteed to be closed paths: contours which intersect the image edge will be left open. All other paths will be closed. (The closedness of a path can be tested by checking whether the beginning point is the same as the end point.)

Produced paths are oriented. Following the path from beginning to end, image intensity values lower than the contour value are to the left of the path and intensity values greater than the contour value are to the right. In other words, the image gradient at a path segment is (approximately) in the direct of that segment rotated right by 90 degrees, because the image intensity values increase from left-to-right across the segment. This means that the generated contours will circle clockwise around "hills" of above-contour-value intensity, and counter-clockwise around "depressions" of below-contour-value intensity. This convention can be reversed by calling ReverseContourOrientationOn().

By default values are interpreted as intensities relative to a contour value. First calling LabelContoursOn() changes this behavior to instead interpret each value as a label. Boundaries are computed for each label separately and all are returned. The value of LabelContours affects the interpretation of VertexConnectHighPixels; see above.

By default the input image's largest possible region will be processed; call SetRequestedRegion() to process a different region, or ClearRequestedRegion() to revert to the default value. Note that the requested regions are usually set on the output; however since paths have no notion of a "region", this must be set at the filter level.

This class was contributed to the Insight Journal by Zachary Pincus. https://doi.org/10.54294/olkmog

See also

itk::ContourExtractor2DImageFilter for the Doxygen on the original ITK class.

Definition at line 80 of file sitkContourExtractor2DImageFilter.h.

Public Types
using	PixelIDTypeList = BasicPixelIDTypeList
using	Self = ContourExtractor2DImageFilter
Public Types inherited from itk::simple::ImageFilter
using	Self = ImageFilter
Public Types inherited from itk::simple::ProcessObject
using	Self = ProcessObject

Public Member Functions
	ContourExtractor2DImageFilter ()
void	Execute (const Image &image1)
std::vector< double >	GetContour (unsigned int n) const
double	GetContourValue () const
bool	GetLabelContours () const
std::string	GetName () const
unsigned int	GetNumberOfCountours () const
bool	GetReverseContourOrientation () const
bool	GetVertexConnectHighPixels () const
void	LabelContoursOff ()
void	LabelContoursOn ()
void	ReverseContourOrientationOff ()
void	ReverseContourOrientationOn ()
void	SetContourValue (double ContourValue)
void	SetLabelContours (bool LabelContours)
void	SetReverseContourOrientation (bool ReverseContourOrientation)
void	SetVertexConnectHighPixels (bool VertexConnectHighPixels)
std::string	ToString () const
void	VertexConnectHighPixelsOff ()
void	VertexConnectHighPixelsOn ()
virtual	~ContourExtractor2DImageFilter ()
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.
virtual int	AddCommand (itk::simple::EventEnum event, itk::simple::Command &cmd)
	Add a Command Object to observer the event.
virtual float	GetProgress () const
	An Active Measurement of the progress of execution.
virtual bool	HasCommand (itk::simple::EventEnum event) const
	Query of this object has any registered commands for event.
	ProcessObject ()
virtual void	RemoveAllCommands ()
	Remove all registered commands.
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 = void (Self::*)(const Image &image1)

Private Member Functions
template<class TImageType>
void	ExecuteInternal (const Image &image1)

Static Private Member Functions
static const detail::MemberFunctionFactory< MemberFunctionType > &	GetMemberFunctionFactory ()

Private Attributes
double	m_ContourValue { 0.0 }
std::unique_ptr< itk::ProcessObject, ProcessObjectDeleter >	m_Filter {nullptr}
bool	m_LabelContours { false }
unsigned int	m_NumberOfCountours { 0 }
std::function< std::vector< double >(unsigned int)>	m_pfGetContour
bool	m_ReverseContourOrientation { false }
bool	m_VertexConnectHighPixels { false }

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.
static void	SetGlobalDefaultCoordinateTolerance (double)
	Access the global tolerance to determine congruent spaces.
static double	GetGlobalDefaultDirectionTolerance ()
	Access the global tolerance to determine congruent spaces.
static void	SetGlobalDefaultDirectionTolerance (double)
	Access the global tolerance to determine congruent spaces.
static bool	SetGlobalDefaultThreader (const std::string &threader)
	Set/Get the default threader used for process objects.
static std::string	GetGlobalDefaultThreader ()
	Set/Get the default threader used for process objects.
static void	SetGlobalDefaultNumberOfThreads (unsigned int n)
static unsigned int	GetGlobalDefaultNumberOfThreads ()
	Set/Get the default threader used for process objects.
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)

Member Typedef Documentation

MemberFunctionType

using itk::simple::ContourExtractor2DImageFilter::MemberFunctionType = void (Self::*)(const Image &image1)

private

Setup for member function dispatching

Definition at line 201 of file sitkContourExtractor2DImageFilter.h.

PixelIDTypeList

using itk::simple::ContourExtractor2DImageFilter::PixelIDTypeList = BasicPixelIDTypeList

Define the pixels types supported by this filter

Definition at line 92 of file sitkContourExtractor2DImageFilter.h.

Self

using itk::simple::ContourExtractor2DImageFilter::Self = ContourExtractor2DImageFilter

Definition at line 82 of file sitkContourExtractor2DImageFilter.h.

Constructor & Destructor Documentation

~ContourExtractor2DImageFilter()

virtual itk::simple::ContourExtractor2DImageFilter::~ContourExtractor2DImageFilter ( )

virtual

Destructor

ContourExtractor2DImageFilter()

itk::simple::ContourExtractor2DImageFilter::ContourExtractor2DImageFilter

(

)

Default Constructor that takes no arguments and initializes default parameters

Member Function Documentation

Execute()

void itk::simple::ContourExtractor2DImageFilter::Execute

(

const Image &

image1

)

Execute the filter on the input image

ExecuteInternal()

template<class TImageType>

void itk::simple::ContourExtractor2DImageFilter::ExecuteInternal ( const Image & image1 )

private

Referenced by detail::MemberFunctionAddressor< MemberFunctionType >.

GetContour()

std::vector< double > itk::simple::ContourExtractor2DImageFilter::GetContour ( unsigned int n ) const

inline

Get the coordinates of the n-th contour path as a flat vector of doubles in the format (x1, y1, x2, y2, ...). The index n should be less than the number of outputs returned by GetNumberOfOutputs().

This is an active measurement. It may be accessed while the filter is being executing in command call-backs and can be accessed after execution.

Definition at line 186 of file sitkContourExtractor2DImageFilter.h.

References m_pfGetContour.

GetContourValue()

double itk::simple::ContourExtractor2DImageFilter::GetContourValue ( ) const

inline

Set/Get the image intensity value that the contours should follow. This is the equivalent of an iso-value in Marching Squares.

Definition at line 109 of file sitkContourExtractor2DImageFilter.h.

References m_ContourValue.

GetLabelContours()

bool itk::simple::ContourExtractor2DImageFilter::GetLabelContours ( ) const

inline

Return contours for all distinct labels

Definition at line 168 of file sitkContourExtractor2DImageFilter.h.

References m_LabelContours.

GetMemberFunctionFactory()

static const detail::MemberFunctionFactory< MemberFunctionType > & itk::simple::ContourExtractor2DImageFilter::GetMemberFunctionFactory ( )

staticprivate

GetName()

std::string itk::simple::ContourExtractor2DImageFilter::GetName ( ) const

inlinevirtual

Name of this class

Implements itk::simple::ProcessObject.

Definition at line 189 of file sitkContourExtractor2DImageFilter.h.

GetNumberOfCountours()

unsigned int itk::simple::ContourExtractor2DImageFilter::GetNumberOfCountours ( ) const

inline

Get the number of contour paths generated. Multiple contours may be produced because an image can have multiple contours at a given level.

This is a measurement. Its value is updated in the Execute methods, so the value will only be valid after an execution.

Definition at line 177 of file sitkContourExtractor2DImageFilter.h.

References m_NumberOfCountours.

GetReverseContourOrientation()

bool itk::simple::ContourExtractor2DImageFilter::GetReverseContourOrientation ( ) const

inline

Control the orientation of the contours with reference to the image gradient. (See class documentation.)

Definition at line 128 of file sitkContourExtractor2DImageFilter.h.

References m_ReverseContourOrientation.

GetVertexConnectHighPixels()

bool itk::simple::ContourExtractor2DImageFilter::GetVertexConnectHighPixels ( ) const

inline

Control whether high- or low-valued pixels are vertex-connected. Default is for low-valued pixels to be vertex- connected. (See class documentation.)

Definition at line 149 of file sitkContourExtractor2DImageFilter.h.

References m_VertexConnectHighPixels.

LabelContoursOff()

void itk::simple::ContourExtractor2DImageFilter::LabelContoursOff ( )

inline

Definition at line 163 of file sitkContourExtractor2DImageFilter.h.

References SetLabelContours().

LabelContoursOn()

void itk::simple::ContourExtractor2DImageFilter::LabelContoursOn ( )

inline

Set the value of LabelContours to true or false respectfully.

Definition at line 161 of file sitkContourExtractor2DImageFilter.h.

References SetLabelContours().

ReverseContourOrientationOff()

void itk::simple::ContourExtractor2DImageFilter::ReverseContourOrientationOff ( )

inline

Definition at line 123 of file sitkContourExtractor2DImageFilter.h.

References SetReverseContourOrientation().

ReverseContourOrientationOn()

void itk::simple::ContourExtractor2DImageFilter::ReverseContourOrientationOn ( )

inline

Set the value of ReverseContourOrientation to true or false respectfully.

Definition at line 121 of file sitkContourExtractor2DImageFilter.h.

References SetReverseContourOrientation().

SetContourValue()

void itk::simple::ContourExtractor2DImageFilter::SetContourValue ( double ContourValue )

inline

Set/Get the image intensity value that the contours should follow. This is the equivalent of an iso-value in Marching Squares.

Definition at line 102 of file sitkContourExtractor2DImageFilter.h.

References m_ContourValue.

SetLabelContours()

void itk::simple::ContourExtractor2DImageFilter::SetLabelContours ( bool LabelContours )

inline

Return contours for all distinct labels

Definition at line 156 of file sitkContourExtractor2DImageFilter.h.

References m_LabelContours.

Referenced by LabelContoursOff(), and LabelContoursOn().

SetReverseContourOrientation()

void itk::simple::ContourExtractor2DImageFilter::SetReverseContourOrientation ( bool ReverseContourOrientation )

inline

Control the orientation of the contours with reference to the image gradient. (See class documentation.)

Definition at line 116 of file sitkContourExtractor2DImageFilter.h.

References m_ReverseContourOrientation.

Referenced by ReverseContourOrientationOff(), and ReverseContourOrientationOn().

SetVertexConnectHighPixels()

void itk::simple::ContourExtractor2DImageFilter::SetVertexConnectHighPixels ( bool VertexConnectHighPixels )

inline

Control whether high- or low-valued pixels are vertex-connected. Default is for low-valued pixels to be vertex- connected. (See class documentation.)

Definition at line 136 of file sitkContourExtractor2DImageFilter.h.

References m_VertexConnectHighPixels.

Referenced by VertexConnectHighPixelsOff(), and VertexConnectHighPixelsOn().

ToString()

std::string itk::simple::ContourExtractor2DImageFilter::ToString ( ) const

virtual

Print ourselves out

Reimplemented from itk::simple::ProcessObject.

VertexConnectHighPixelsOff()

void itk::simple::ContourExtractor2DImageFilter::VertexConnectHighPixelsOff ( )

inline

Definition at line 143 of file sitkContourExtractor2DImageFilter.h.

References SetVertexConnectHighPixels().

VertexConnectHighPixelsOn()

void itk::simple::ContourExtractor2DImageFilter::VertexConnectHighPixelsOn ( )

inline

Set the value of VertexConnectHighPixels to true or false respectfully.

Definition at line 141 of file sitkContourExtractor2DImageFilter.h.

References SetVertexConnectHighPixels().

Friends And Related Symbol Documentation

detail::MemberFunctionAddressor< MemberFunctionType >

friend struct detail::MemberFunctionAddressor< MemberFunctionType >

friend

Definition at line 202 of file sitkContourExtractor2DImageFilter.h.

References ExecuteInternal().

Member Data Documentation

m_ContourValue

double itk::simple::ContourExtractor2DImageFilter::m_ContourValue { 0.0 }

private

Definition at line 207 of file sitkContourExtractor2DImageFilter.h.

Referenced by GetContourValue(), and SetContourValue().

m_Filter

std::unique_ptr<itk::ProcessObject, ProcessObjectDeleter> itk::simple::ContourExtractor2DImageFilter::m_Filter {nullptr}

private

Definition at line 222 of file sitkContourExtractor2DImageFilter.h.

m_LabelContours

bool itk::simple::ContourExtractor2DImageFilter::m_LabelContours { false }

private

Definition at line 213 of file sitkContourExtractor2DImageFilter.h.

Referenced by GetLabelContours(), and SetLabelContours().

m_NumberOfCountours

unsigned int itk::simple::ContourExtractor2DImageFilter::m_NumberOfCountours { 0 }

private

Definition at line 217 of file sitkContourExtractor2DImageFilter.h.

Referenced by GetNumberOfCountours().

m_pfGetContour

std::function<std::vector<double>(unsigned int)> itk::simple::ContourExtractor2DImageFilter::m_pfGetContour

private

Definition at line 218 of file sitkContourExtractor2DImageFilter.h.

Referenced by GetContour().

m_ReverseContourOrientation

bool itk::simple::ContourExtractor2DImageFilter::m_ReverseContourOrientation { false }

private

Definition at line 209 of file sitkContourExtractor2DImageFilter.h.

Referenced by GetReverseContourOrientation(), and SetReverseContourOrientation().

m_VertexConnectHighPixels

bool itk::simple::ContourExtractor2DImageFilter::m_VertexConnectHighPixels { false }

private

Definition at line 211 of file sitkContourExtractor2DImageFilter.h.

Referenced by GetVertexConnectHighPixels(), and SetVertexConnectHighPixels().

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

• sitkContourExtractor2DImageFilter.h