#include <itkSobelOperator.h>

Detailed Description

template<typename TPixel, unsigned int VDimension = 2, typename TAllocator = NeighborhoodAllocator<TPixel>>
class itk::SobelOperator< TPixel, VDimension, TAllocator >

A NeighborhoodOperator for performing a directional Sobel edge-detection operation at a pixel location.

SobelOperator is a directional NeighborhoodOperator that should be applied a NeighborhoodIterator using the NeighborhoodInnerProduct method. To create the operator:

1) Set the direction by calling

SetDirection

itk::NeighborhoodOperator< TPixel, 2, NeighborhoodAllocator< TPixel > >::SetDirection

void SetDirection(const unsigned long direction)

Definition: itkNeighborhoodOperator.h:94

2) call

constexpr auto radius = itk::Size<2>::Filled(1);

sobelOperator.CreateToRadius(radius);

itk::Size::Filled

static constexpr Self Filled(const SizeValueType value)

Definition: itkSize.h:425

3) You may optionally scale the coefficients of this operator using the

ScaleCoefficients

itk::NeighborhoodOperator< TPixel, 2, NeighborhoodAllocator< TPixel > >::ScaleCoefficients

void ScaleCoefficients(PixelRealType)

method. This is useful if you want to take the spacing of the image into account when computing the edge strength. Apply the scaling only after calling to

CreateToRadius

itk::NeighborhoodOperator< TPixel, 2, NeighborhoodAllocator< TPixel > >::CreateToRadius

virtual void CreateToRadius(const SizeType &)

.

The Sobel Operator in vertical direction for 2 dimensions is

*             -1  -2  -1
*             0    0   0
*             1    2   1
*
*

The Sobel Operator in horizontal direction is for 2 dimensions is

*             -1   0   1
*             -2   0   2
*             -1   0   1
*

The current implementation of the Sobel operator is for 2 and 3 dimensions only. The ND version is planned for future releases.

The extension to 3D is from the publication "Irwin Sobel. An Isotropic 3x3x3 Volume Gradient Operator. Technical report, Hewlett-Packard Laboratories, April 1995."

The Sobel operator in 3D has the kernel

* -1 -3 -1   0 0 0  1 3 1
* -3 -6 -3   0 0 0  3 6 3
* -1 -3 -1   0 0 0  1 3 1
*
*    x-1       x     x+1
*

The x kernel is just rotated as required to obtain the kernel in the y and z directions.

Note: SobelOperator does not have any user-declared "special member function", following the C++ Rule of Zero: the compiler will generate them if necessary.

See also: NeighborhoodOperator; Neighborhood; ForwardDifferenceOperator; BackwardDifferenceOperator

ITK Sphinx Examples:

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Definition at line 97 of file itkSobelOperator.h.

Inheritance diagram for itk::SobelOperator< TPixel, VDimension, TAllocator >:

Collaboration diagram for itk::SobelOperator< TPixel, VDimension, TAllocator >:

Public Types
using	Self = SobelOperator

using	Superclass = NeighborhoodOperator< TPixel, VDimension, TAllocator >

Public Types inherited from itk::NeighborhoodOperator< TPixel, 2, NeighborhoodAllocator< TPixel > >
using	PixelRealType = typename NumericTraits< TPixel >::RealType

using	PixelType = TPixel

using	Self = NeighborhoodOperator

using	SizeType = itk::Size< VDimension >

using	SliceIteratorType = SliceIterator< TPixel, Self >

using	Superclass = Neighborhood< TPixel, VDimension, NeighborhoodAllocator< TPixel > >

Public Types inherited from itk::Neighborhood< TPixel, VDimension, NeighborhoodAllocator< TPixel > >
using	AllocatorType = NeighborhoodAllocator< TPixel >

using	ConstIterator = typename AllocatorType::const_iterator

using	DimensionValueType = unsigned int

using	Iterator = typename AllocatorType::iterator

using	NeighborIndexType = SizeValueType

using	OffsetType = Offset< VDimension >

using	PixelType = TPixel

using	RadiusType = itk::Size< VDimension >

using	Self = Neighborhood

using	SizeType = itk::Size< VDimension >

using	SizeValueType = typename SizeType::SizeValueType

using	SliceIteratorType = SliceIterator< TPixel, Self >

Public Member Functions
void	CreateDirectional () override

const char *	GetNameOfClass () const override

Public Member Functions inherited from itk::NeighborhoodOperator< TPixel, 2, NeighborhoodAllocator< TPixel > >
virtual void	CreateDirectional ()

virtual void	CreateToRadius (const SizeType &)

virtual void	CreateToRadius (const SizeValueType)

virtual void	FlipAxes ()

unsigned long	GetDirection () const

const char *	GetNameOfClass () const override

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

void	ScaleCoefficients (PixelRealType)

void	SetDirection (const unsigned long direction)

Public Member Functions inherited from itk::Neighborhood< TPixel, VDimension, NeighborhoodAllocator< TPixel > >
NeighborIndexType	GetCenterNeighborhoodIndex () const

TPixel	GetCenterValue () const

virtual const char *	GetNameOfClass () const

virtual NeighborIndexType	GetNeighborhoodIndex (const OffsetType &) const

OffsetType	GetOffset (NeighborIndexType i) const

const SizeType	GetRadius () const

SizeValueType	GetRadius (DimensionValueType n) const

SizeType	GetSize () const

SizeValueType	GetSize (DimensionValueType n) const

std::slice	GetSlice (unsigned int) const

OffsetValueType	GetStride (DimensionValueType axis) const

	ITK_UNEQUAL_OPERATOR_MEMBER_FUNCTION (Self)

	Neighborhood ()=default

	Neighborhood (const Self &)=default

	Neighborhood (Self &&)=default

Self &	operator= (const Self &)=default

Self &	operator= (Self &&)=default

bool	operator== (const Self &other) const

void	Print (std::ostream &os) const

void	SetRadius (const SizeType &)

void	SetRadius (const SizeValueType)

NeighborIndexType	Size () const

virtual	~Neighborhood ()=default

Iterator	End ()

ConstIterator	End () const

Iterator	Begin ()

ConstIterator	Begin () const

TPixel &	operator[] (NeighborIndexType i)

const TPixel &	operator[] (NeighborIndexType i) const

TPixel &	GetElement (NeighborIndexType i)

TPixel &	operator[] (const OffsetType &o)

const TPixel &	operator[] (const OffsetType &o) const

void	SetRadius (const SizeValueType *rad)

AllocatorType &	GetBufferReference ()

const AllocatorType &	GetBufferReference () const

Protected Types
using	CoefficientVector = typename std::vector< PixelRealType >

Protected Types inherited from itk::NeighborhoodOperator< TPixel, 2, NeighborhoodAllocator< TPixel > >
using	CoefficientVector = typename std::vector< PixelRealType >

Protected Member Functions
void	Fill (const CoefficientVector &coeff) override

CoefficientVector	GenerateCoefficients () override

Protected Member Functions inherited from itk::NeighborhoodOperator< TPixel, 2, NeighborhoodAllocator< TPixel > >
virtual void	Fill (const CoefficientVector &)=0

virtual void	FillCenteredDirectional (const CoefficientVector &)

virtual CoefficientVector	GenerateCoefficients ()=0

void	InitializeToZero ()

Protected Member Functions inherited from itk::Neighborhood< TPixel, VDimension, NeighborhoodAllocator< TPixel > >
virtual void	Allocate (NeighborIndexType i)

virtual void	ComputeNeighborhoodOffsetTable ()

virtual void	ComputeNeighborhoodStrideTable ()

virtual void	PrintSelf (std::ostream &, Indent) const

void	SetSize ()

Additional Inherited Members
Static Public Attributes inherited from itk::Neighborhood< TPixel, VDimension, NeighborhoodAllocator< TPixel > >
static constexpr unsigned int	NeighborhoodDimension

Member Typedef Documentation

◆ CoefficientVector

template<typename TPixel , unsigned int VDimension = 2, typename TAllocator = NeighborhoodAllocator<TPixel>>

using itk::NeighborhoodOperator< TPixel, VDimension, TAllocator >::CoefficientVector = typename std::vector<PixelRealType>

protected

Type alias support for coefficient vector type. Necessary to fix bug in the microsoft VC++ compiler.

Definition at line 153 of file itkNeighborhoodOperator.h.

◆ Self

template<typename TPixel , unsigned int VDimension = 2, typename TAllocator = NeighborhoodAllocator<TPixel>>

using itk::SobelOperator< TPixel, VDimension, TAllocator >::Self = SobelOperator

Standard class type aliases.

Definition at line 102 of file itkSobelOperator.h.

◆ Superclass

template<typename TPixel , unsigned int VDimension = 2, typename TAllocator = NeighborhoodAllocator<TPixel>>

using itk::SobelOperator< TPixel, VDimension, TAllocator >::Superclass = NeighborhoodOperator<TPixel, VDimension, TAllocator>

Definition at line 103 of file itkSobelOperator.h.

Member Function Documentation

◆ CreateDirectional()

template<typename TPixel , unsigned int VDimension = 2, typename TAllocator = NeighborhoodAllocator<TPixel>>

void itk::SobelOperator< TPixel, VDimension, TAllocator >::CreateDirectional ( )

inlineoverridevirtual

Creates the operator with length only in the specified direction. The radius of the operator will be 0 except along the axis on which the operator will work.