itk::SobelOperator< TPixel, VDimension, TAllocator > Class Template Reference

#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 

2) call

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

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

ScaleCoefficients 

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 

.

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:

• All ITK Sphinx Examples

• Create Sobel Kernel

Examples

Examples/Iterators/NeighborhoodIterators2.cxx, Examples/Iterators/NeighborhoodIterators3.cxx, SphinxExamples/src/Core/Common/CreateSobelKernel/Code.cxx, SphinxExamples/src/Core/Common/DemonstrateAllOperators/Code.cxx, SphinxExamples/src/Filtering/ImageFilterBase/ApplyKernelToEveryPixel/Code.cxx, and SphinxExamples/src/Filtering/ImageFilterBase/ApplyKernelToEveryPixelInNonZeroImage/Code.cxx.

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, VDimension, TAllocator >
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, TAllocator >
Public Types inherited from itk::Neighborhood< TPixel, VDimension, TAllocator >
using	AllocatorType = TAllocator
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, VDimension, TAllocator >
virtual void	CreateToRadius (const SizeType &)
virtual void	CreateToRadius (const SizeValueType)
virtual void	FlipAxes ()
unsigned long	GetDirection () const
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, TAllocator >
NeighborIndexType	GetCenterNeighborhoodIndex () const
TPixel	GetCenterValue () 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 ()
Iterator	Begin ()
ConstIterator	End () const
ConstIterator	Begin () const
TPixel &	operator[] (NeighborIndexType i)
const TPixel &	operator[] (NeighborIndexType i) const
TPixel &	GetElement (NeighborIndexType i)
void	SetRadius (const SizeValueType *rad)
AllocatorType &	GetBufferReference ()
const AllocatorType &	GetBufferReference () const
TPixel &	operator[] (const OffsetType &o)
const TPixel &	operator[] (const OffsetType &o) const

Protected Member Functions
void	Fill (const CoefficientVector &coeff) override
CoefficientVector	GenerateCoefficients () override
Protected Member Functions inherited from itk::NeighborhoodOperator< TPixel, VDimension, TAllocator >
virtual void	FillCenteredDirectional (const CoefficientVector &)
void	InitializeToZero ()
Protected Member Functions inherited from itk::Neighborhood< TPixel, VDimension, TAllocator >
virtual void	Allocate (NeighborIndexType i)
virtual void	ComputeNeighborhoodOffsetTable ()
virtual void	ComputeNeighborhoodStrideTable ()
void	SetSize ()

Additional Inherited Members
Static Public Attributes inherited from itk::Neighborhood< TPixel, VDimension, TAllocator >
static constexpr unsigned int	NeighborhoodDimension = VDimension
Protected Types inherited from itk::NeighborhoodOperator< TPixel, VDimension, TAllocator >
using	CoefficientVector = typename std::vector< PixelRealType >

Member Typedef Documentation

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.

See also

CreateToRadius

FillCenteredDirectional

SetDirection()

GetDirection()

Reimplemented from itk::NeighborhoodOperator< TPixel, VDimension, TAllocator >.

Definition at line 112 of file itkSobelOperator.h.

Fill()

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

void itk::SobelOperator< TPixel, VDimension, TAllocator >::Fill ( const CoefficientVector &  coeff )

overrideprotectedvirtual

Arranges coefficients spatially in the memory buffer.

Implements itk::NeighborhoodOperator< TPixel, VDimension, TAllocator >.

GenerateCoefficients()

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

CoefficientVector itk::SobelOperator< TPixel, VDimension, TAllocator >::GenerateCoefficients ( )

overrideprotectedvirtual

Calculates operator coefficients.

Implements itk::NeighborhoodOperator< TPixel, VDimension, TAllocator >.

GetNameOfClass()

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

const char* itk::SobelOperator< TPixel, VDimension, TAllocator >::GetNameOfClass ( ) const

overridevirtual

See also

LightObject::GetNameOfClass()

Reimplemented from itk::NeighborhoodOperator< TPixel, VDimension, TAllocator >.

---

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

• itkSobelOperator.h