A class for doing multi-dimensional convolution. More...

#include <LatticeConvolver.h>

Public Member Functions
	LatticeConvolver ()
	The default constructor creates a LatticeConvolver that will convolve your data with a point spread function (psf) that zero everywhere except at the centre where it is one.
	LatticeConvolver (const Lattice< T > &psf, Bool doFast=False)
	Create a convolver that is initialised to do circular convolution with the specified point spread function.
	LatticeConvolver (const Lattice< T > &psf, const IPosition &modelShape, Bool doFast=False)
	Create a convolver that is initialised to do linear convolution with the specified point spread function.
	LatticeConvolver (const Lattice< T > &psf, const IPosition &modelShape, ConvEnums::ConvType type, Bool doFast=False)
	Create a convolver that is initialised to do the specified type of convolution with the specified point spread function.
	LatticeConvolver (const LatticeConvolver< T > &other)
	The copy constructor uses reference semantics.
LatticeConvolver< T > &	operator= (const LatticeConvolver< T > &other)
	The assignment operator also uses reference semantics.
	~LatticeConvolver ()
	The destructor does nothing special.
void	linear (Lattice< T > &result, const Lattice< T > &model)
	Perform linear convolution of the model with the previously specified psf.
void	linear (Lattice< T > &modelAndResult)
	Perform in-place linear convolution of the model with the previously specified psf.
void	circular (Lattice< T > &result, const Lattice< T > &model)
	Perform circular convolution of the model with the previously specified psf.
void	circular (Lattice< T > &modelAndResult)
	Perform in-place linear convolution of the model with the previously specified psf.
void	convolve (Lattice< T > &modelAndResult) const
	Perform convolution on the specified model using the currently initialised convolution type (linear or circular).
void	convolve (Lattice< T > &result, const Lattice< T > &model) const
void	getPsf (Lattice< T > &psf) const
	Return the psf currently used by this convolver.
void	resize (const IPosition &modelShape, ConvEnums::ConvType type)
	Resize the LatticeConvolver to do convolutions of the specified type and shape.
IPosition	shape () const
	Returns the shape of the Lattices that the convolver will convolve.
IPosition	psfShape () const
	Returns the shape of the point spread function that the LatticeConvolver was initialised with.
ConvEnums::ConvType	type () const
	Returns the type of convolution the LatticeConvolver is currently set up to do.
IPosition	fftShape () const
	Returns the shape of the FFT's that the LatticeConvolver will do when performing the convolution.
void	setFastConvolve ()
	Set usage of fast convolve with lesser flips.
Private Member Functions
void	makeXfr (const Lattice< T > &psf)
void	makePsf (Lattice< T > &psf) const
Static Private Member Functions
static void	pad (Lattice< T > &paddedLat, const Lattice< T > &inLat)
static void	unpad (Lattice< T > &result, const Lattice< T > &paddedResult)
static IPosition	calcFFTShape (const IPosition &psfShape, const IPosition &modelShape, ConvEnums::ConvType type)
Private Attributes
IPosition	itsPsfShape
IPosition	itsModelShape
ConvEnums::ConvType	itsType
IPosition	itsFFTShape
TempLattice< typename NumericTraits< T > ::ConjugateType > *	itsXfr
TempLattice< T > *	itsPsf
Bool	itsCachedPsf
Bool	doFast_p

Detailed Description

template<class T>
class casa::LatticeConvolver< T >

A class for doing multi-dimensional convolution.

Intended use:

Public interface

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Prerequisite

The mathematical concept of convolution

Etymology

The LatticeConvolver class will convolve Lattices. This class complements the Convolver class which will convolve Arrays.

Synopsis

This class performs linear or circular convolution on Lattices. See the Convolver class description of the difference between linear and circular convolution.

This class does convolutions by multiplying the Fourier transforms of the supplied Lattices and returning the inverse transform of the product. This is the best algorithm to use when the point spread function is large. This class does all the padding with zeros necessary to implement this algorithm. Hence the

Example

Motivation

Thrown Exceptions

AipsError: if psf and model have a differing numbers of dimensions

To Do

the class should detect if the psf or image is small and do the convolution directly rather than use the Fourier domain
Allow the psf to be specified with a Function .

Definition at line 110 of file LatticeConvolver.h.

Constructor & Destructor Documentation

template<class T>

casa::LatticeConvolver< T >::LatticeConvolver ( )

The default constructor creates a LatticeConvolver that will convolve your data with a point spread function (psf) that zero everywhere except at the centre where it is one.

Convolving with this psf will not change your data.

template<class T>

casa::LatticeConvolver< T >::LatticeConvolver	(	const Lattice< T > &	psf,
		Bool	doFast = `False`
	)

Create a convolver that is initialised to do circular convolution with the specified point spread function.

It is assumed that the supplied model will be the same shape as the point spread function.

template<class T>

casa::LatticeConvolver< T >::LatticeConvolver	(	const Lattice< T > &	psf,
		const IPosition &	modelShape,
		Bool	doFast = `False`
	)

Create a convolver that is initialised to do linear convolution with the specified point spread function.

The size of the model you will convolve with must be specified.

template<class T>

casa::LatticeConvolver< T >::LatticeConvolver	(	const Lattice< T > &	psf,
		const IPosition &	modelShape,
		ConvEnums::ConvType	type,
		Bool	doFast = `False`
	)

Create a convolver that is initialised to do the specified type of convolution with the specified point spread function.

The size of the model you expect to convolve with must be specified.

template<class T>

casa::LatticeConvolver< T >::LatticeConvolver ( const LatticeConvolver< T > & other )

The copy constructor uses reference semantics.

template<class T>

casa::LatticeConvolver< T >::~LatticeConvolver ( )

The destructor does nothing special.

Member Function Documentation

template<class T>

static IPosition casa::LatticeConvolver< T >::calcFFTShape	(	const IPosition &	psfShape,
		const IPosition &	modelShape,
		ConvEnums::ConvType	type
	)		`[static, private]`

template<class T>

void casa::LatticeConvolver< T >::circular	(	Lattice< T > &	result,
		const Lattice< T > &	model
	)

Perform circular convolution of the model with the previously specified psf.

Return the answer in result.

template<class T>

void casa::LatticeConvolver< T >::circular ( Lattice< T > & modelAndResult )

Perform in-place linear convolution of the model with the previously specified psf.

Return the result in the same Lattice as the model.

template<class T>

void casa::LatticeConvolver< T >::convolve ( Lattice< T > & modelAndResult ) const

Perform convolution on the specified model using the currently initialised convolution type (linear or circular).

These functions will not resize the LatticeConvolver if the supplied Lattice is the wrong shape.

If the LatticeConvolver is setup for circular Convolution then the size of the supplied model must be less than or equal to the shape returned by the fftshape() function, which is usually the same as the shape of the psf.

If the LatticeConvolver is setup to do linear convolution the the input and output Lattices must have the same shape as the result from the shape() member function. The convolution may be either in-place or not.

template<class T>

void casa::LatticeConvolver< T >::convolve	(	Lattice< T > &	result,
		const Lattice< T > &	model
	)		const

template<class T>

IPosition casa::LatticeConvolver< T >::fftShape ( ) const

Returns the shape of the FFT's that the LatticeConvolver will do when performing the convolution.

Not really useful except as a diagnostic tool. If the shape contains a lot of poorly factorisable lengths then the convolution will be slow.

template<class T>

void casa::LatticeConvolver< T >::getPsf ( Lattice< T > & psf ) const

Return the psf currently used by this convolver.

The supplied Lattice must be the correct shape ie., the same as returned by the psfShape member function.

template<class T>

void casa::LatticeConvolver< T >::linear	(	Lattice< T > &	result,
		const Lattice< T > &	model
	)

Perform linear convolution of the model with the previously specified psf.

The supplied Lattices must be the same shape.

template<class T>

void casa::LatticeConvolver< T >::linear ( Lattice< T > & modelAndResult )

Perform in-place linear convolution of the model with the previously specified psf.

Return the result in the same Lattice as the model.

template<class T>

void casa::LatticeConvolver< T >::makePsf ( Lattice< T > & psf ) const [private]

template<class T>

void casa::LatticeConvolver< T >::makeXfr ( const Lattice< T > & psf ) [private]

template<class T>

LatticeConvolver<T>& casa::LatticeConvolver< T >::operator= ( const LatticeConvolver< T > & other )

The assignment operator also uses reference semantics.

template<class T>

static void casa::LatticeConvolver< T >::pad	(	Lattice< T > &	paddedLat,
		const Lattice< T > &	inLat
	)		`[static, private]`

template<class T>

IPosition casa::LatticeConvolver< T >::psfShape ( ) const

Returns the shape of the point spread function that the LatticeConvolver was initialised with.

template<class T>

void casa::LatticeConvolver< T >::resize	(	const IPosition &	modelShape,
		ConvEnums::ConvType	type
	)

Resize the LatticeConvolver to do convolutions of the specified type and shape.

The supplied function must always have the same number of dimensions as the internal point spread function (which can be found using the shape member function). The LatticeConvolver will be set up to do circular or linear convolutions depending on the supplied type

template<class T>

void casa::LatticeConvolver< T >::setFastConvolve ( )

Set usage of fast convolve with lesser flips.

template<class T>

IPosition casa::LatticeConvolver< T >::shape ( ) const

Returns the shape of the Lattices that the convolver will convolve.

This shape will always have as many dimensions as the psf that was used to initialise the LatticeConvolver. If the LatticeConvolver is setup to do circular convolutions then every axis of the returned IPosition will be zero length. If the LatticeConvolver is setup to do linear convolutions then the returned IPosition will have a positive values on each axis that indicate the expected shape of the input model.

template<class T>

ConvEnums::ConvType casa::LatticeConvolver< T >::type ( ) const

Returns the type of convolution the LatticeConvolver is currently set up to do.

template<class T>