ITK  6.0.0
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itk::FrequencyShiftedFFTLayoutImageRegionConstIteratorWithIndex< TImage > Class Template Reference
Data Access Objects » Iterators » Image Iterators | Group Filtering » Module ITKImageFrequency

#include <itkFrequencyShiftedFFTLayoutImageRegionConstIteratorWithIndex.h>

Detailed Description

template<typename TImage>
class itk::FrequencyShiftedFFTLayoutImageRegionConstIteratorWithIndex< TImage >

A multi-dimensional iterator templated over image type that walks pixels within a region and is specialized to keep track of its image index location.

This class is a specialization of ImageRegionConstIteratorWithIndex, adding method GetFrequencyBins to give the frequency bins corresponding to image indices, and GetFrequency to get the frequency of the bin. The frequency bins depends on the image size. The default assumes that the image to iterate over is the output of a forward FFT filter, where the first index corresponds to 0 frequency, and Nyquist Frequencies are in the middle, between positive and negative frequencies.

This class can be specialized further to iterate over other frequency layouts, for example shifted images (where 0 frequency is in the middle of the image, and Nyquist are in the border). For different layout, use other frequency iterator.

This iterator is for the frequency layout that results from applying a FFT (vnl or fftw) to an image. The default ImageInformation is: Origin = {{0}}, Spacing = {{1}}. In this case the frequency values will be in the range: [-1/2, 1/2] Hz Or [-pi, pi] rad/s To modify those ranges: a) Avoid modifying the origin. The origin index always corresponds to zero frequency after a FFT. The range should be always centered around zero. b) The spacing control the range of frequencies (always around zero). If the spacing is = {{0.5}} we get a frequency range of [-1/4, 1/4] or [-pi/2, pi/2].

The frequency layout is assumed to be: where fs is frequency sampling, or frequency spacing (1.0 by default). If N is even: Nyquist frequency at index=N/2 is shared between + and - regions. <---------—positive f ------------—><---------—negative f-----------—> 0(DC) fs/N 2*fs/N ... (N/2 -1)*fs/N fs/2 -(N/2-1)*fs/N ... -2*fs/N -fs/N

Example: Size 6:

+ | -

0 <– DC Component (0 freq) 1 | 5 2 | 4 3 <– Shared between regions, unique Nyquist.

If N is odd: Nyquist frequency is not represented but there are symmetric largest frequencies at index=N/2, N/2 +1 <-------—positive f ------------—><---------—negative f--------------—> 0(DC) fs/N 2*fs/N ...... fs/2*(N-1)/N -fs/2*(N-1)/N ... -2*fs/N -fs/N

Example: Size 5:

+ | -

0 <– DC Component (0 freq) 1 | 4 2 | 3 <– Absolute Largest Frequency bins (+, -)

Please see ImageRegionConstIteratorWithIndex for more information.

See also
ForwardFFTImageFilter
MORE INFORMATION
For a complete description of the ITK Image Iterators and their API, please see the Iterators chapter in the ITK Software Guide. The ITK Software Guide is available in print and as a free .pdf download from https://www.itk.org.
See also
ImageRegionIteratorWithIndex
ImageConstIterator
ConditionalConstIterator
ConstNeighborhoodIterator
ConstShapedNeighborhoodIterator
ConstSliceIterator
CorrespondenceDataStructureIterator
FloodFilledFunctionConditionalConstIterator
FloodFilledImageFunctionConditionalConstIterator
FloodFilledImageFunctionConditionalIterator
FloodFilledSpatialFunctionConditionalConstIterator
FloodFilledSpatialFunctionConditionalIterator
ImageConstIterator
ImageConstIteratorWithIndex
ImageIterator
ImageIteratorWithIndex
ImageLinearConstIteratorWithIndex
ImageLinearIteratorWithIndex
ImageRandomConstIteratorWithIndex
ImageRandomIteratorWithIndex
ImageRegionConstIterator
ImageRegionConstIteratorWithIndex
ImageRegionExclusionConstIteratorWithIndex
ImageRegionExclusionIteratorWithIndex
ImageRegionIterator
ImageRegionIteratorWithIndex
ImageRegionReverseConstIterator
ImageRegionReverseIterator
ImageReverseConstIterator
ImageReverseIterator
ImageSliceConstIteratorWithIndex
ImageSliceIteratorWithIndex
NeighborhoodIterator
PathConstIterator
PathIterator
ShapedNeighborhoodIterator
SliceIterator
ImageConstIteratorWithIndex

Definition at line 115 of file itkFrequencyShiftedFFTLayoutImageRegionConstIteratorWithIndex.h.

+ Inheritance diagram for itk::FrequencyShiftedFFTLayoutImageRegionConstIteratorWithIndex< TImage >:
+ Collaboration diagram for itk::FrequencyShiftedFFTLayoutImageRegionConstIteratorWithIndex< TImage >:

Public Types

using AccessorType = typename TImage::AccessorType
 
using FrequencyType = typename ImageType::SpacingType
 
using FrequencyValueType = typename ImageType::SpacingValueType
 
using ImageType = TImage
 
using IndexType = typename TImage::IndexType
 
using InternalPixelType = typename TImage::InternalPixelType
 
using OffsetType = typename TImage::OffsetType
 
using PixelContainer = typename TImage::PixelContainer
 
using PixelContainerPointer = typename PixelContainer::Pointer
 
using PixelType = typename TImage::PixelType
 
using RegionType = typename TImage::RegionType
 
using Self = FrequencyShiftedFFTLayoutImageRegionConstIteratorWithIndex
 
using SizeType = typename TImage::SizeType
 
using Superclass = ImageRegionConstIteratorWithIndex< TImage >
 
- Public Types inherited from itk::ImageRegionConstIteratorWithIndex< TImage >
using AccessorType = typename TImage::AccessorType
 
using ImageType = TImage
 
using IndexType = typename TImage::IndexType
 
using InternalPixelType = typename TImage::InternalPixelType
 
using OffsetType = typename TImage::OffsetType
 
using PixelContainer = typename TImage::PixelContainer
 
using PixelContainerPointer = typename PixelContainer::Pointer
 
using PixelType = typename TImage::PixelType
 
using RegionType = typename TImage::RegionType
 
using Self = ImageRegionConstIteratorWithIndex
 
using SizeType = typename TImage::SizeType
 
using Superclass = ImageConstIteratorWithIndex< TImage >
 
- Public Types inherited from itk::ImageConstIteratorWithIndex< TImage >
using AccessorFunctorType = typename TImage::AccessorFunctorType
 
using AccessorType = typename TImage::AccessorType
 
using ImageType = TImage
 
using IndexType = typename TImage::IndexType
 
using IndexValueType = typename IndexType::IndexValueType
 
using InternalPixelType = typename TImage::InternalPixelType
 
using OffsetType = typename TImage::OffsetType
 
using OffsetValueType = typename OffsetType::OffsetValueType
 
using PixelContainer = typename TImage::PixelContainer
 
using PixelContainerPointer = typename PixelContainer::Pointer
 
using PixelType = typename TImage::PixelType
 
using RegionType = typename TImage::RegionType
 
using Self = ImageConstIteratorWithIndex
 
using SizeType = typename TImage::SizeType
 
using SizeValueType = typename SizeType::SizeValueType
 

Public Member Functions

 FrequencyShiftedFFTLayoutImageRegionConstIteratorWithIndex ()
 
 FrequencyShiftedFFTLayoutImageRegionConstIteratorWithIndex (const Superclass &it)
 
 FrequencyShiftedFFTLayoutImageRegionConstIteratorWithIndex (const TImage *ptr, const RegionType &region)
 
IndexType GetFrequencyBin () const
 
FrequencyValueType GetFrequencyModuloSquare () const
 
virtual const FrequencyType & GetFrequencyOrigin () const
 
virtual const FrequencyType & GetFrequencySpacing () const
 
virtual const IndexType & GetZeroFrequencyIndex () const
 
FrequencyType GetFrequency () const
 
void SetActualXDimensionIsOdd (bool value)
 
virtual bool GetActualXDimensionIsOdd ()
 
virtual void ActualXDimensionIsOddOn ()
 
- Public Member Functions inherited from itk::ImageRegionConstIteratorWithIndex< TImage >
 ImageRegionConstIteratorWithIndex ()
 
 ImageRegionConstIteratorWithIndex (const ImageConstIteratorWithIndex< TImage > &it)
 
 ImageRegionConstIteratorWithIndex (const TImage *ptr, const RegionType &region)
 
Self & operator++ ()
 
Self & operator-- ()
 
- Public Member Functions inherited from itk::ImageConstIteratorWithIndex< TImage >
PixelType Get () const
 
const IndexType & GetIndex () const
 
const RegionType & GetRegion () const
 
void GoToBegin ()
 
void GoToReverseBegin ()
 
 ImageConstIteratorWithIndex ()=default
 
 ImageConstIteratorWithIndex (const Self &it)
 
 ImageConstIteratorWithIndex (const TImage *ptr, const RegionType &region)
 
bool IsAtEnd () const
 
bool IsAtReverseEnd () const
 
 ITK_UNEQUAL_OPERATOR_MEMBER_FUNCTION (Self)
 
bool operator< (const Self &it) const
 
bool operator<= (const Self &it) const
 
Self & operator= (const Self &it)
 
bool operator== (const Self &it) const
 
bool operator> (const Self &it) const
 
bool operator>= (const Self &it) const
 
bool Remaining ()
 
const PixelType & Value () const
 
virtual ~ImageConstIteratorWithIndex ()=default
 
void SetIndex (const IndexType &ind)
 

Private Member Functions

void Init ()
 

Private Attributes

bool m_ActualXDimensionIsOdd
 
FrequencyType m_FrequencyOrigin
 
FrequencyType m_FrequencySpacing
 
IndexType m_ZeroFrequencyIndex
 

Additional Inherited Members

- Static Public Member Functions inherited from itk::ImageConstIteratorWithIndex< TImage >
static constexpr unsigned int GetImageDimension ()
 
- Static Public Attributes inherited from itk::ImageConstIteratorWithIndex< TImage >
static constexpr unsigned int ImageDimension = TImage::ImageDimension
 
- Protected Attributes inherited from itk::ImageConstIteratorWithIndex< TImage >
const InternalPixelType * m_Begin { nullptr }
 
IndexType m_BeginIndex { { 0 } }
 
const InternalPixelType * m_End { nullptr }
 
IndexType m_EndIndex { { 0 } }
 
TImage::ConstWeakPointer m_Image {}
 
OffsetValueType m_OffsetTable [ImageDimension+1] {}
 
AccessorType m_PixelAccessor {}
 
AccessorFunctorType m_PixelAccessorFunctor {}
 
const InternalPixelType * m_Position { nullptr }
 
IndexType m_PositionIndex { { 0 } }
 
RegionType m_Region {}
 
bool m_Remaining { false }
 

Member Typedef Documentation

◆ AccessorType

template<typename TImage >
using itk::ImageConstIteratorWithIndex< TImage >::AccessorType = typename TImage::AccessorType

Accessor type that converts data between internal and external representations.

Definition at line 132 of file itkImageConstIteratorWithIndex.h.

◆ FrequencyType

template<typename TImage >
using itk::FrequencyShiftedFFTLayoutImageRegionConstIteratorWithIndex< TImage >::FrequencyType = typename ImageType::SpacingType

Definition at line 136 of file itkFrequencyShiftedFFTLayoutImageRegionConstIteratorWithIndex.h.

◆ FrequencyValueType

template<typename TImage >
using itk::FrequencyShiftedFFTLayoutImageRegionConstIteratorWithIndex< TImage >::FrequencyValueType = typename ImageType::SpacingValueType

Definition at line 137 of file itkFrequencyShiftedFFTLayoutImageRegionConstIteratorWithIndex.h.

◆ ImageType

template<typename TImage >
using itk::ImageConstIteratorWithIndex< TImage >::ImageType = TImage

Image type alias support

Definition at line 116 of file itkImageConstIteratorWithIndex.h.

◆ IndexType

template<typename TImage >
using itk::ImageConstIteratorWithIndex< TImage >::IndexType = typename TImage::IndexType

Index type alias support

Definition at line 105 of file itkImageConstIteratorWithIndex.h.

◆ InternalPixelType

template<typename TImage >
using itk::ImageConstIteratorWithIndex< TImage >::InternalPixelType = typename TImage::InternalPixelType

Internal Pixel Type

Definition at line 125 of file itkImageConstIteratorWithIndex.h.

◆ OffsetType

template<typename TImage >
using itk::ImageConstIteratorWithIndex< TImage >::OffsetType = typename TImage::OffsetType

Type of the Offset taken from the image

Definition at line 136 of file itkImageConstIteratorWithIndex.h.

◆ PixelContainer

template<typename TImage >
using itk::ImageConstIteratorWithIndex< TImage >::PixelContainer = typename TImage::PixelContainer

PixelContainer type alias support Used to refer to the container for the pixel data. While this was already typedef'ed in the superclass, it needs to be redone here for this subclass to compile properly with gcc.

Definition at line 121 of file itkImageConstIteratorWithIndex.h.

◆ PixelContainerPointer

template<typename TImage >
using itk::ImageConstIteratorWithIndex< TImage >::PixelContainerPointer = typename PixelContainer::Pointer

Definition at line 122 of file itkImageConstIteratorWithIndex.h.

◆ PixelType

template<typename TImage >
using itk::ImageConstIteratorWithIndex< TImage >::PixelType = typename TImage::PixelType

External Pixel Type

Definition at line 128 of file itkImageConstIteratorWithIndex.h.

◆ RegionType

template<typename TImage >
using itk::ImageConstIteratorWithIndex< TImage >::RegionType = typename TImage::RegionType

Region type alias support

Definition at line 113 of file itkImageConstIteratorWithIndex.h.

◆ Self

template<typename TImage >
using itk::FrequencyShiftedFFTLayoutImageRegionConstIteratorWithIndex< TImage >::Self = FrequencyShiftedFFTLayoutImageRegionConstIteratorWithIndex

Standard class type alias.

Definition at line 121 of file itkFrequencyShiftedFFTLayoutImageRegionConstIteratorWithIndex.h.

◆ SizeType

template<typename TImage >
using itk::ImageConstIteratorWithIndex< TImage >::SizeType = typename TImage::SizeType

Size type alias support

Definition at line 109 of file itkImageConstIteratorWithIndex.h.

◆ Superclass

template<typename TImage >
using itk::FrequencyShiftedFFTLayoutImageRegionConstIteratorWithIndex< TImage >::Superclass = ImageRegionConstIteratorWithIndex<TImage>

Definition at line 122 of file itkFrequencyShiftedFFTLayoutImageRegionConstIteratorWithIndex.h.

Constructor & Destructor Documentation

◆ FrequencyShiftedFFTLayoutImageRegionConstIteratorWithIndex() [1/3]

template<typename TImage >
itk::FrequencyShiftedFFTLayoutImageRegionConstIteratorWithIndex< TImage >::FrequencyShiftedFFTLayoutImageRegionConstIteratorWithIndex ( )
inline

Default constructor. Needed since we provide a cast constructor.

Definition at line 139 of file itkFrequencyShiftedFFTLayoutImageRegionConstIteratorWithIndex.h.

◆ FrequencyShiftedFFTLayoutImageRegionConstIteratorWithIndex() [2/3]

template<typename TImage >
itk::FrequencyShiftedFFTLayoutImageRegionConstIteratorWithIndex< TImage >::FrequencyShiftedFFTLayoutImageRegionConstIteratorWithIndex ( const TImage *  ptr,
const RegionType &  region 
)
inline

Constructor establishes an iterator to walk a particular image and a particular region of that image. Initializes the iterator at the begin of the region.

Definition at line 147 of file itkFrequencyShiftedFFTLayoutImageRegionConstIteratorWithIndex.h.

◆ FrequencyShiftedFFTLayoutImageRegionConstIteratorWithIndex() [3/3]

template<typename TImage >
itk::FrequencyShiftedFFTLayoutImageRegionConstIteratorWithIndex< TImage >::FrequencyShiftedFFTLayoutImageRegionConstIteratorWithIndex ( const Superclass &  it)
inlineexplicit

Constructor that can be used to cast from an ImageIterator to an ImageRegionIteratorWithIndex. Many routines return an ImageIterator, but for a particular task, you may want an ImageRegionIteratorWithIndex. Rather than provide overloaded APIs that return different types of Iterators, itk returns ImageIterators and uses constructors to cast from an ImageIterator to a ImageRegionIteratorWithIndex.

Definition at line 159 of file itkFrequencyShiftedFFTLayoutImageRegionConstIteratorWithIndex.h.

Member Function Documentation

◆ ActualXDimensionIsOddOn()

template<typename TImage >
virtual void itk::FrequencyShiftedFFTLayoutImageRegionConstIteratorWithIndex< TImage >::ActualXDimensionIsOddOn ( )
virtual

Does nothing. This member only affects HalfHermitianFrequencyIterator. Provided for homogeneous interface between iterators.

◆ GetActualXDimensionIsOdd()

template<typename TImage >
virtual bool itk::FrequencyShiftedFFTLayoutImageRegionConstIteratorWithIndex< TImage >::GetActualXDimensionIsOdd ( )
virtual

Does nothing. This member only affects HalfHermitianFrequencyIterator. Provided for homogeneous interface between iterators.

◆ GetFrequency()

template<typename TImage >
FrequencyType itk::FrequencyShiftedFFTLayoutImageRegionConstIteratorWithIndex< TImage >::GetFrequency ( ) const
inline

Note that this method is independent of the region in the constructor. It takes into account the ImageInformation of the Image in the frequency domain. This iterator is for the frequency layout that results from applying a FFT and then ShiftFFT to center the zero frequency component. If your image has a different layout, use other frequency iterator. The default ImageInformation is: Origin = {{0}}, Spacing = {{1}}. In this case the frequency values will be in the range: [-1/2, 1/2] Hz Or [-pi, pi] rad/s To modify those ranges: a) Avoid modifying the origin. The origin index always corresponds to zero frequency after a FFT. The range should be always centered around zero. b) The spacing control the range of frequencies (always around zero). If the spacing is = {{0.5}} we get a frequency range of [-1/4, 1/4] or [-pi/2, pi/2].

Definition at line 192 of file itkFrequencyShiftedFFTLayoutImageRegionConstIteratorWithIndex.h.

◆ GetFrequencyBin()

template<typename TImage >
IndexType itk::FrequencyShiftedFFTLayoutImageRegionConstIteratorWithIndex< TImage >::GetFrequencyBin ( ) const
inline

Definition at line 171 of file itkFrequencyShiftedFFTLayoutImageRegionConstIteratorWithIndex.h.

◆ GetFrequencyModuloSquare()

template<typename TImage >
FrequencyValueType itk::FrequencyShiftedFFTLayoutImageRegionConstIteratorWithIndex< TImage >::GetFrequencyModuloSquare ( ) const
inline

Definition at line 206 of file itkFrequencyShiftedFFTLayoutImageRegionConstIteratorWithIndex.h.

◆ GetFrequencyOrigin()

template<typename TImage >
virtual const FrequencyType & itk::FrequencyShiftedFFTLayoutImageRegionConstIteratorWithIndex< TImage >::GetFrequencyOrigin ( ) const
virtual

Origin of frequencies is zero for FFT output.

◆ GetFrequencySpacing()

template<typename TImage >
virtual const FrequencyType & itk::FrequencyShiftedFFTLayoutImageRegionConstIteratorWithIndex< TImage >::GetFrequencySpacing ( ) const
virtual

This is the pixel width, or the bin size of the frequency in physical or world coordinates. SamplingFrequency = 1.0 / SpatialImageSpacing FrequencySpacing = SamplingFrequency / ImageSize FrequencySpacing = 1.0 / (SpatialImageSpacing * ImageSize) FrequencySpacing is computed at construction from the spacing of the input image, and cannot be modified.

◆ GetZeroFrequencyIndex()

template<typename TImage >
virtual const IndexType & itk::FrequencyShiftedFFTLayoutImageRegionConstIteratorWithIndex< TImage >::GetZeroFrequencyIndex ( ) const
virtual

Index with the zero frequency value. By default: ZeroFrequencyIndex = floor(sizeImage / 2); This is: N/2 if N even, (N - 1)/2 if N odd.

◆ Init()

template<typename TImage >
void itk::FrequencyShiftedFFTLayoutImageRegionConstIteratorWithIndex< TImage >::Init ( )
inlineprivate

Calculate m_ZeroFrequencyIndex, and frequency spacing/origin. Called by constructors.

Definition at line 252 of file itkFrequencyShiftedFFTLayoutImageRegionConstIteratorWithIndex.h.

◆ SetActualXDimensionIsOdd()

template<typename TImage >
void itk::FrequencyShiftedFFTLayoutImageRegionConstIteratorWithIndex< TImage >::SetActualXDimensionIsOdd ( bool  value)
inline

Does nothing. This member only affects HalfHermitianFrequencyIterator. Provided for homogeneous interface between iterators.

Definition at line 240 of file itkFrequencyShiftedFFTLayoutImageRegionConstIteratorWithIndex.h.

Member Data Documentation

◆ m_ActualXDimensionIsOdd

template<typename TImage >
bool itk::FrequencyShiftedFFTLayoutImageRegionConstIteratorWithIndex< TImage >::m_ActualXDimensionIsOdd
private

Definition at line 273 of file itkFrequencyShiftedFFTLayoutImageRegionConstIteratorWithIndex.h.

◆ m_FrequencyOrigin

template<typename TImage >
FrequencyType itk::FrequencyShiftedFFTLayoutImageRegionConstIteratorWithIndex< TImage >::m_FrequencyOrigin
private

Definition at line 271 of file itkFrequencyShiftedFFTLayoutImageRegionConstIteratorWithIndex.h.

◆ m_FrequencySpacing

template<typename TImage >
FrequencyType itk::FrequencyShiftedFFTLayoutImageRegionConstIteratorWithIndex< TImage >::m_FrequencySpacing
private

Definition at line 272 of file itkFrequencyShiftedFFTLayoutImageRegionConstIteratorWithIndex.h.

◆ m_ZeroFrequencyIndex

template<typename TImage >
IndexType itk::FrequencyShiftedFFTLayoutImageRegionConstIteratorWithIndex< TImage >::m_ZeroFrequencyIndex
private

Definition at line 270 of file itkFrequencyShiftedFFTLayoutImageRegionConstIteratorWithIndex.h.

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