Polarimetric analysis of images. More...

#include <ImagePolarimetry.h>

Public Types
enum	StokesTypes { I, Q, U, V }
	casacore::Stokes types More...

Public Member Functions
	ImagePolarimetry (const casacore::ImageInterface< casacore::Float > &image)
	Constructor. More...

	ImagePolarimetry (const ImagePolarimetry &other)
	Copy constructor (reference semantics) More...

	~ImagePolarimetry ()
	Destructor. More...

ImagePolarimetry &	operator= (const ImagePolarimetry &other)
	Assignment operator (reference semantics) More...

void	summary (casacore::LogIO &os) const
	Summary. More...

SPCIIF	imageInterface () const
	Get the casacore::ImageInterface pointer of the construction image Don't delete it ! More...

casacore::CoordinateSystem	coordinates () const
	Get the casacore::CoordinateSystem of the construction image. More...

casacore::IPosition	shape () const
	Get the shape of the construction image. More...

casacore::Bool	isMasked () const
	Is the construction image masked ? More...

casacore::IPosition	singleStokesShape (casacore::CoordinateSystem &cSys, casacore::Stokes::StokesTypes type) const
	Get the shape and casacore::CoordinateSystem of an image for a single Stokes pixel. More...

casacore::ImageExpr < casacore::Complex >	complexLinearPolarization ()
	Complex linear polarization. More...

casacore::ImageExpr < casacore::Complex >	complexFractionalLinearPolarization ()
	casacore::Complex fractional linear polarization More...

casacore::ImageExpr < casacore::Float >	stokesI () const
	Get the Stokes I image and the standard deviation of the I image. More...

casacore::Float	sigmaStokesI (casacore::Float clip=10.0)

casacore::ImageExpr < casacore::Float >	stokesQ () const
	Get the casacore::Stokes Q image and the standard deviation of the Q image. More...

casacore::Float	sigmaStokesQ (casacore::Float clip=10.0)

casacore::ImageExpr < casacore::Float >	stokesU () const
	Get the casacore::Stokes U image and the standard deviation of the U image. More...

casacore::Float	sigmaStokesU (casacore::Float clip=10.0)

casacore::ImageExpr < casacore::Float >	stokesV () const
	Get the casacore::Stokes V image and the standard deviation of the V image. More...

casacore::Float	sigmaStokesV (casacore::Float clip=10.0)

casacore::ImageExpr < casacore::Float >	stokes (ImagePolarimetry::StokesTypes index) const
	Get the specified casacore::Stokes image and the standard deviation of the image. More...

casacore::Float	sigmaStokes (ImagePolarimetry::StokesTypes index, casacore::Float clip=10.0)

casacore::Float	sigma (casacore::Float clip=10.0)
	Get the best estimate of the statistical noise. More...

casacore::Float	sigmaLinPolInt (casacore::Float clip=10.0, casacore::Float sigma=-1.0)
	Get the linearly polarized intensity image and its standard deviation. More...

casacore::ImageExpr < casacore::Float >	totPolInt (casacore::Bool debias, casacore::Float clip=10.0, casacore::Float sigma=-1.0)
	Get the total polarized intensity (from whatever combination of Q, U, and V the construction image has) image and its error (standard deviation). More...

casacore::Float	sigmaTotPolInt (casacore::Float clip=10.0, casacore::Float sigma=-1.0)

casacore::ImageExpr < casacore::Float >	linPolPosAng (casacore::Bool radians) const
	Get linearly polarized position angle (degrees or radians) image and error (standard deviation). More...

casacore::ImageExpr < casacore::Float >	sigmaLinPolPosAng (casacore::Bool radians, casacore::Float clip=10.0, casacore::Float sigma=-1.0)

casacore::ImageExpr < casacore::Float >	fracLinPol (casacore::Bool debias, casacore::Float clip=10.0, casacore::Float sigma=-1.0)
	Get fractional linear polarization image and error (standard deviation). More...

casacore::ImageExpr < casacore::Float >	sigmaFracLinPol (casacore::Float clip=10.0, casacore::Float sigma=-1.0)

casacore::ImageExpr < casacore::Float >	fracTotPol (casacore::Bool debias, casacore::Float clip=10.0, casacore::Float sigma=-1.0)
	Get Fractional total polarization and error (standard deviation) `var` is the standard deviation of the thermal noise. More...

casacore::ImageExpr < casacore::Float >	sigmaFracTotPol (casacore::Float clip=10.0, casacore::Float sigma=-1.0)

void	fourierRotationMeasure (casacore::ImageInterface< casacore::Complex > &pol, casacore::Bool zeroZeroLag)
	Fourier Rotation Measure. More...

casacore::IPosition	rotationMeasureShape (casacore::CoordinateSystem &cSys, casacore::Int &frequencyAxis, casacore::Int &stokesAxis, casacore::LogIO &os, casacore::Int spectralAxis=-1) const
	This function is used in concert with the rotationMeasure function. More...

casacore::IPosition	positionAngleShape (casacore::CoordinateSystem &cSys, casacore::Int &frequencyAxis, casacore::Int &stokesAxis, casacore::LogIO &os, casacore::Int spectralAxis=-1) const
	This function is used in concert with the rotationMeasure function. More...

void	rotationMeasure (casacore::ImageInterface< casacore::Float > &rmPtr, casacore::ImageInterface< casacore::Float > &rmErrPtr, casacore::ImageInterface< casacore::Float > &pa0Ptr, casacore::ImageInterface< casacore::Float > &pa0ErrPtr, casacore::ImageInterface< casacore::Float > &nTurns, casacore::ImageInterface< casacore::Float > &rChiSqPtr, casacore::Int spectralAxis, casacore::Float rmMax, casacore::Float maxPaErr=1.0e30, casacore::Float sigma=-1.0, casacore::Float rmFg=0.0, casacore::Bool showProgress=false)
	This function applies a traditional (i.e. More...

Static Public Member Functions
static casacore::ImageExpr < casacore::Float >	depolarizationRatio (const casacore::ImageInterface< casacore::Float > &im1, const casacore::ImageInterface< casacore::Float > &im2, casacore::Bool debias, casacore::Float clip=10.0, casacore::Float sigma=-1.0)
	Depolarization ratio image and error. More...

static casacore::ImageExpr < casacore::Float >	sigmaDepolarizationRatio (const casacore::ImageInterface< casacore::Float > &im1, const casacore::ImageInterface< casacore::Float > &im2, casacore::Bool debias, casacore::Float clip=10.0, casacore::Float sigma=-1.0)

Private Member Functions
void	_cleanup ()
	Delete all private pointers. More...

casacore::Bool	_dealWithMask (casacore::Lattice< casacore::Bool > &pMask, casacore::ImageInterface< casacore::Float > &pIm, casacore::LogIO &os, const casacore::String &type) const
	For traiditional RM approach, give output a mask if possible. More...

void	_fiddleStokesCoordinate (casacore::ImageInterface< casacore::Float > &ie, casacore::Stokes::StokesTypes type) const
	Change the Stokes Coordinate for the given float image to be of the specified Stokes type. More...

void	_fiddleStokesCoordinate (casacore::CoordinateSystem &cSys, casacore::Stokes::StokesTypes type) const

void	_fiddleStokesCoordinate (casacore::ImageInterface< casacore::Complex > &ie, casacore::Stokes::StokesTypes type) const
	Change the casacore::Stokes casacore::Coordinate for the given complex image to be of the specified casacore::Stokes type. More...

void	_fiddleTimeCoordinate (casacore::ImageInterface< casacore::Complex > &ie, const casacore::Quantum< casacore::Double > &f, casacore::Int coord) const
	Change the time coordinate to be rotation measure. More...

casacore::Quantum < casacore::Double >	_findCentralFrequency (const casacore::Coordinate &coord, casacore::Int shape) const
	Find the central frequency from the given spectral coordinate. More...

casacore::Bool	_findRotationMeasure (casacore::Float &rmFitted, casacore::Float &rmErrFitted, casacore::Float &pa0Fitted, casacore::Float &pa0ErrFitted, casacore::Float &rChiSqFitted, casacore::Float &nTurns, const casacore::Vector< casacore::uInt > &sortidx, const casacore::Vector< casacore::Float > &wsq, const casacore::Vector< casacore::Float > &pa, const casacore::Array< casacore::Bool > &paMask, const casacore::Array< casacore::Float > &paerr, casacore::Float rmfg, casacore::Float rmmax, casacore::Float paErrMax, const casacore::String &posString)
	Fit the spectrum of position angles to find the rotation measure via Leahy algorithm. More...

void	_findStokes ()
	Find the casacore::Stokes in the construction image and assign pointers. More...

casacore::Int	_findSpectralCoordinate (const casacore::CoordinateSystem &cSys, casacore::LogIO &os, casacore::Bool fail) const
	Find the spectral coordinate. More...

void	_findFrequencyAxis (casacore::Int &spectralCoord, casacore::Int &fAxis, const casacore::CoordinateSystem &cSys, casacore::Int spectralAxis) const
	FInd frequency axis. More...

void	_hasQU () const
	So we have Q and U ? Excpetion if not. More...

casacore::LatticeExprNode	_makePolIntNode (casacore::LogIO &os, casacore::Bool debias, casacore::Float clip, casacore::Float sigma, casacore::Bool doLin, casacore::Bool doCirc)
	Make a LEN for the give types of polarized intensity. More...

casacore::ImageExpr < casacore::Float >	_makeStokesExpr (casacore::ImageInterface< casacore::Float > *imPtr, casacore::Stokes::StokesTypes type, const casacore::String &name) const
	Make an IE for the specified Stokes. More...

casacore::ImageInterface < casacore::Float > *	_makeSubImage (casacore::IPosition &blc, casacore::IPosition &trc, casacore::Int axis, casacore::Int pix) const
	Make a casacore::SubImage from the construction image for the specified pixel along the specified pixel axis. More...

casacore::Bool	_rmLsqFit (casacore::Vector< casacore::Float > &pars, const casacore::Vector< casacore::Float > &wsq, const casacore::Vector< casacore::Float > pa, const casacore::Vector< casacore::Float > &paerr) const
	Least squares fit to find RM from position angles. More...

casacore::Bool	_rmPrimaryFit (casacore::Float &nTurns, casacore::Float &rmFitted, casacore::Float &rmErrFitted, casacore::Float &pa0Fitted, casacore::Float &pa0ErrFitted, casacore::Float &rChiSqFitted, const casacore::Vector< casacore::Float > &wsq, const casacore::Vector< casacore::Float > &pa, const casacore::Vector< casacore::Float > &paerr, casacore::Float rmmax, const casacore::String &posString)
	Fit the spectrum of position angles to find the rotation measure via Leahy algorithm for primary (n>2) points. More...

casacore::Bool	_rmSupplementaryFit (casacore::Float &nTurns, casacore::Float &rmFitted, casacore::Float &rmErrFitted, casacore::Float &pa0Fitted, casacore::Float &pa0ErrFitted, casacore::Float &rChiSqFitted, const casacore::Vector< casacore::Float > &wsq, const casacore::Vector< casacore::Float > &pa, const casacore::Vector< casacore::Float > &paerr)
	Fit the spectrum of position angles to find the rotation measure via Leahy algorithm for supplementary (n==2) points. More...

casacore::String	_stokesName (ImagePolarimetry::StokesTypes index) const
	Return I, Q, U or V for specified integer index (0-3) More...

casacore::Stokes::StokesTypes	_stokesType (ImagePolarimetry::StokesTypes index) const
	Return I, Q, U or V for specified integer index (0-3) More...

casacore::Float	_sigma (ImagePolarimetry::StokesTypes index, casacore::Float clip)
	Find the standard deviation for the Stokes image specified by the integer index. More...

void	_subtractProfileMean (casacore::ImageInterface< casacore::Float > &im, casacore::uInt axis) const
	Subtract profile mean from image. More...

void	_createBeamsEqMat ()

casacore::Bool	_checkBeams (const std::vector< StokesTypes > &stokes, casacore::Bool requireChannelEquality, casacore::Bool throws=true) const

casacore::Bool	_checkIQUBeams (casacore::Bool requireChannelEquality, casacore::Bool throws=true) const

casacore::Bool	_checkIVBeams (casacore::Bool requireChannelEquality, casacore::Bool throws=true) const

casacore::Bool	_checkQUBeams (casacore::Bool requireChannelEquality, casacore::Bool throws=true) const

void	_setInfo (casacore::ImageInterface< casacore::Complex > &im, StokesTypes stokes) const

void	_setInfo (casacore::ImageInterface< casacore::Float > &im, StokesTypes stokes) const

void	_setDoLinDoCirc (casacore::Bool &doLin, casacore::Bool &doCirc) const

Static Private Member Functions
static void	_checkBeams (const ImagePolarimetry &im1, const ImagePolarimetry &im2, const casacore::Vector< StokesTypes > &stokes)

Private Attributes
SPCIIF	_image

casacore::LinearFitSVD < casacore::Float > *	_fitter
	const casacore::ImageInterface<casacore::Float>* _image; More...

casacore::Float	_oldClip

casacore::PtrBlock < casacore::ImageInterface < casacore::Float > * >	_stokes
	These blocks are always size 4, with IQUV in slots 0,1,2,3 If your image is IV only, they still use slots 0 and 3. More...

casacore::PtrBlock < casacore::LatticeStatistics < casacore::Float > * >	_stokesStats

casacore::Matrix< casacore::Bool >	_beamsEqMat

Static Private Attributes
static const map< StokesTypes, casacore::String >	polMap

Detailed Description

Polarimetric analysis of images.

Intended use:

Public interface

Review Status

Date Reviewed:: yyyy/mm/dd

Prerequisite

ImageExpr
ImageInterface

Etymology

Polarimetric analysis of Images

Synopsis

This class provides polarimetric image analysis capability. It takes an image with a casacore::Stokes axis (some combination of IQUV is needed) as its input.

Many functions return casacore::ImageExpr objects. These are read-only images.

Sometimes the standard deviation of the noise is needed. This is for debiasing polarized intensity images or working out error images. By default it is worked out for you with a clipped mean algorithm. However, you can provide sigma if you know it accurately. It should be the standard deviation of the noise in the absence of signal. You won't measure that very well from casacore::Stokes I if it is dynamic range limited. Better to get it from V or Q or U. When this class needs the standard deviation of the noise, it will try and get it from V or Q and U and finally I.

However, note that the functions sigmaStokes{I,Q,U,V} DO return the standard deviation of the noise for that specific casacore::Stokes type.

The ImageExpr objects returned have the brightness units and ImageInfo set. The MiscInfo (a permanent record) and logSink are not set.

Motivation

Basic image analysis capability

To Do

plotting for function rotationMeasure
some assessment of the curvature of pa-l**2

Definition at line 109 of file ImagePolarimetry.h.

Member Enumeration Documentation

enum casa::ImagePolarimetry::StokesTypes

casacore::Stokes types

Enumerator
I
Q
U
V

Definition at line 113 of file ImagePolarimetry.h.

Constructor & Destructor Documentation

casa::ImagePolarimetry::ImagePolarimetry ( const casacore::ImageInterface< casacore::Float > & image )

Constructor.

The input image must have a Stokes axis with some subset of I,Q,U, and V

casa::ImagePolarimetry::ImagePolarimetry ( const ImagePolarimetry & other )

Copy constructor (reference semantics)

casa::ImagePolarimetry::~ImagePolarimetry ( )

Destructor.

Member Function Documentation

casacore::Bool casa::ImagePolarimetry::_checkBeams	(	const std::vector< StokesTypes > &	stokes,
		casacore::Bool	requireChannelEquality,
		casacore::Bool	throws = `true`
	)		const

private

static void casa::ImagePolarimetry::_checkBeams	(	const ImagePolarimetry &	im1,
		const ImagePolarimetry &	im2,
		const casacore::Vector< StokesTypes > &	stokes
	)

staticprivate

casacore::Bool casa::ImagePolarimetry::_checkIQUBeams	(	casacore::Bool	requireChannelEquality,
		casacore::Bool	throws = `true`
	)		const

private

casacore::Bool casa::ImagePolarimetry::_checkIVBeams	(	casacore::Bool	requireChannelEquality,
		casacore::Bool	throws = `true`
	)		const

private

casacore::Bool casa::ImagePolarimetry::_checkQUBeams	(	casacore::Bool	requireChannelEquality,
		casacore::Bool	throws = `true`
	)		const

private

void casa::ImagePolarimetry::_cleanup ( )

private

Delete all private pointers.

void casa::ImagePolarimetry::_createBeamsEqMat ( )

private

casacore::Bool casa::ImagePolarimetry::_dealWithMask	(	casacore::Lattice< casacore::Bool > *&	pMask,
		casacore::ImageInterface< casacore::Float > *&	pIm,
		casacore::LogIO &	os,
		const casacore::String &	type
	)		const

private

For traiditional RM approach, give output a mask if possible.

void casa::ImagePolarimetry::_fiddleStokesCoordinate	(	casacore::ImageInterface< casacore::Float > &	ie,
		casacore::Stokes::StokesTypes	type
	)		const

private

Change the Stokes Coordinate for the given float image to be of the specified Stokes type.

void casa::ImagePolarimetry::_fiddleStokesCoordinate	(	casacore::CoordinateSystem &	cSys,
		casacore::Stokes::StokesTypes	type
	)		const

private

void casa::ImagePolarimetry::_fiddleStokesCoordinate	(	casacore::ImageInterface< casacore::Complex > &	ie,
		casacore::Stokes::StokesTypes	type
	)		const

private

Change the casacore::Stokes casacore::Coordinate for the given complex image to be of the specified casacore::Stokes type.

void casa::ImagePolarimetry::_fiddleTimeCoordinate	(	casacore::ImageInterface< casacore::Complex > &	ie,
		const casacore::Quantum< casacore::Double > &	f,
		casacore::Int	coord
	)		const

private

Change the time coordinate to be rotation measure.

casacore::Quantum<casacore::Double> casa::ImagePolarimetry::_findCentralFrequency	(	const casacore::Coordinate &	coord,
		casacore::Int	shape
	)		const

private

Find the central frequency from the given spectral coordinate.

void casa::ImagePolarimetry::_findFrequencyAxis	(	casacore::Int &	spectralCoord,
		casacore::Int &	fAxis,
		const casacore::CoordinateSystem &	cSys,
		casacore::Int	spectralAxis
	)		const

private

FInd frequency axis.

casacore::Bool casa::ImagePolarimetry::_findRotationMeasure	(	casacore::Float &	rmFitted,
		casacore::Float &	rmErrFitted,
		casacore::Float &	pa0Fitted,
		casacore::Float &	pa0ErrFitted,
		casacore::Float &	rChiSqFitted,
		casacore::Float &	nTurns,
		const casacore::Vector< casacore::uInt > &	sortidx,
		const casacore::Vector< casacore::Float > &	wsq,
		const casacore::Vector< casacore::Float > &	pa,
		const casacore::Array< casacore::Bool > &	paMask,
		const casacore::Array< casacore::Float > &	paerr,
		casacore::Float	rmfg,
		casacore::Float	rmmax,
		casacore::Float	paErrMax,
		const casacore::String &	posString
	)

private

Fit the spectrum of position angles to find the rotation measure via Leahy algorithm.

casacore::Int casa::ImagePolarimetry::_findSpectralCoordinate	(	const casacore::CoordinateSystem &	cSys,
		casacore::LogIO &	os,
		casacore::Bool	fail
	)		const

private

Find the spectral coordinate.

void casa::ImagePolarimetry::_findStokes ( )

private

Find the casacore::Stokes in the construction image and assign pointers.

void casa::ImagePolarimetry::_hasQU ( ) const

private

So we have Q and U ? Excpetion if not.

casacore::LatticeExprNode casa::ImagePolarimetry::_makePolIntNode	(	casacore::LogIO &	os,
		casacore::Bool	debias,
		casacore::Float	clip,
		casacore::Float	sigma,
		casacore::Bool	doLin,
		casacore::Bool	doCirc
	)

private

Make a LEN for the give types of polarized intensity.

casacore::ImageExpr<casacore::Float> casa::ImagePolarimetry::_makeStokesExpr	(	casacore::ImageInterface< casacore::Float > *	imPtr,
		casacore::Stokes::StokesTypes	type,
		const casacore::String &	name
	)		const

private

Make an IE for the specified Stokes.

casacore::ImageInterface<casacore::Float>* casa::ImagePolarimetry::_makeSubImage	(	casacore::IPosition &	blc,
		casacore::IPosition &	trc,
		casacore::Int	axis,
		casacore::Int	pix
	)		const

private

Make a casacore::SubImage from the construction image for the specified pixel along the specified pixel axis.

casacore::Bool casa::ImagePolarimetry::_rmLsqFit	(	casacore::Vector< casacore::Float > &	pars,
		const casacore::Vector< casacore::Float > &	wsq,
		const casacore::Vector< casacore::Float >	pa,
		const casacore::Vector< casacore::Float > &	paerr
	)		const

private

Least squares fit to find RM from position angles.

casacore::Bool casa::ImagePolarimetry::_rmPrimaryFit	(	casacore::Float &	nTurns,
		casacore::Float &	rmFitted,
		casacore::Float &	rmErrFitted,
		casacore::Float &	pa0Fitted,
		casacore::Float &	pa0ErrFitted,
		casacore::Float &	rChiSqFitted,
		const casacore::Vector< casacore::Float > &	wsq,
		const casacore::Vector< casacore::Float > &	pa,
		const casacore::Vector< casacore::Float > &	paerr,
		casacore::Float	rmmax,
		const casacore::String &	posString
	)

private

Fit the spectrum of position angles to find the rotation measure via Leahy algorithm for primary (n>2) points.

casacore::Bool casa::ImagePolarimetry::_rmSupplementaryFit	(	casacore::Float &	nTurns,
		casacore::Float &	rmFitted,
		casacore::Float &	rmErrFitted,
		casacore::Float &	pa0Fitted,
		casacore::Float &	pa0ErrFitted,
		casacore::Float &	rChiSqFitted,
		const casacore::Vector< casacore::Float > &	wsq,
		const casacore::Vector< casacore::Float > &	pa,
		const casacore::Vector< casacore::Float > &	paerr
	)

private

Fit the spectrum of position angles to find the rotation measure via Leahy algorithm for supplementary (n==2) points.

void casa::ImagePolarimetry::_setDoLinDoCirc	(	casacore::Bool &	doLin,
		casacore::Bool &	doCirc
	)		const

private

void casa::ImagePolarimetry::_setInfo	(	casacore::ImageInterface< casacore::Complex > &	im,
		StokesTypes	stokes
	)		const

private

void casa::ImagePolarimetry::_setInfo	(	casacore::ImageInterface< casacore::Float > &	im,
		StokesTypes	stokes
	)		const

private

casacore::Float casa::ImagePolarimetry::_sigma	(	ImagePolarimetry::StokesTypes	index,
		casacore::Float	clip
	)

private

Find the standard deviation for the Stokes image specified by the integer index.

casacore::String casa::ImagePolarimetry::_stokesName ( ImagePolarimetry::StokesTypes index ) const

private

Return I, Q, U or V for specified integer index (0-3)

casacore::Stokes::StokesTypes casa::ImagePolarimetry::_stokesType ( ImagePolarimetry::StokesTypes index ) const

private

Return I, Q, U or V for specified integer index (0-3)

void casa::ImagePolarimetry::_subtractProfileMean	(	casacore::ImageInterface< casacore::Float > &	im,
		casacore::uInt	axis
	)		const

private

Subtract profile mean from image.

casacore::ImageExpr<casacore::Complex> casa::ImagePolarimetry::complexFractionalLinearPolarization ( )

casacore::Complex fractional linear polarization

casacore::ImageExpr<casacore::Complex> casa::ImagePolarimetry::complexLinearPolarization ( )

Complex linear polarization.

casacore::CoordinateSystem casa::ImagePolarimetry::coordinates ( ) const

inline

Get the casacore::CoordinateSystem of the construction image.

Definition at line 139 of file ImagePolarimetry.h.

References _image.

static casacore::ImageExpr<casacore::Float> casa::ImagePolarimetry::depolarizationRatio	(	const casacore::ImageInterface< casacore::Float > &	im1,
		const casacore::ImageInterface< casacore::Float > &	im2,
		casacore::Bool	debias,
		casacore::Float	clip = `10.0`,
		casacore::Float	sigma = `-1.0`
	)

static

Depolarization ratio image and error.

Requires two images hence static functions.

void casa::ImagePolarimetry::fourierRotationMeasure	(	casacore::ImageInterface< casacore::Complex > &	pol,
		casacore::Bool	zeroZeroLag
	)

Fourier Rotation Measure.

The output image is the complex polarization (Q + iU) with the spectral axis replaced by a RotationMeasure axis. The appropriate shape and casacore::CoordinateSystem must be obtained with function singleStokesShape (ask for type STokes::Plinear). Howeverm this function will replace the casacore::SpectralCoordinate by a LinearCoordinate describing the Rotation Measure. casacore::ImageInfo, and Units are copied to the output. MiscInfo and history are not. If the output has a mask, and the input is masked, the mask is copied. If the output has a mask, it should already have been initialized to true

casacore::ImageExpr<casacore::Float> casa::ImagePolarimetry::fracLinPol	(	casacore::Bool	debias,
		casacore::Float	clip = `10.0`,
		casacore::Float	sigma = `-1.0`
	)

Get fractional linear polarization image and error (standard deviation).

If wish to debias the image, you can either provide sigma (the standard deviation of the termal noise) or if sigma is non-positive, it will be worked out for you with a clipped mean algorithm.

casacore::ImageExpr<casacore::Float> casa::ImagePolarimetry::fracTotPol	(	casacore::Bool	debias,
		casacore::Float	clip = `10.0`,
		casacore::Float	sigma = `-1.0`
	)

Get Fractional total polarization and error (standard deviation) var is the standard deviation of the thermal noise.

If sigma is non-positive, it will be worked out for you with a clipped mean algorithm.

SPCIIF casa::ImagePolarimetry::imageInterface ( ) const

inline

Get the casacore::ImageInterface pointer of the construction image Don't delete it !

Definition at line 134 of file ImagePolarimetry.h.

References _image.

Referenced by casa::ImagePol::getImage().

casacore::Bool casa::ImagePolarimetry::isMasked ( ) const

inline

Is the construction image masked ?

Definition at line 149 of file ImagePolarimetry.h.

References _image.

casacore::ImageExpr<casacore::Float> casa::ImagePolarimetry::linPolPosAng ( casacore::Bool radians ) const

Get linearly polarized position angle (degrees or radians) image and error (standard deviation).

If you provide sigma it is the standard deviation of the termal noise. If sigma is non-positive, it will be worked out for you with a clipped mean algorithm.

ImagePolarimetry& casa::ImagePolarimetry::operator= ( const ImagePolarimetry & other )

Assignment operator (reference semantics)

casacore::IPosition casa::ImagePolarimetry::positionAngleShape	(	casacore::CoordinateSystem &	cSys,
		casacore::Int &	frequencyAxis,
		casacore::Int &	stokesAxis,
		casacore::LogIO &	os,
		casacore::Int	spectralAxis = `-1`
	)		const

This function is used in concert with the rotationMeasure function.

It tells you what the shape of the output Position Angle image should be, and gives you its CoordinateSystem. Because the ImagePolarimetry construction image may house the frequencies coordinate description in a Spectral, Tabular or Linear coordinate, you may explicitly specify which axis is the Spectral axis (spectralAxis). By default, it tries to find the SpectralCoordinate. If there is none, it will look for Tabular or Linear coordinates with a "FREQ" label.

void casa::ImagePolarimetry::rotationMeasure	(	casacore::ImageInterface< casacore::Float > *&	rmPtr,
		casacore::ImageInterface< casacore::Float > *&	rmErrPtr,
		casacore::ImageInterface< casacore::Float > *&	pa0Ptr,
		casacore::ImageInterface< casacore::Float > *&	pa0ErrPtr,
		casacore::ImageInterface< casacore::Float > *&	nTurns,
		casacore::ImageInterface< casacore::Float > *&	rChiSqPtr,
		casacore::Int	spectralAxis,
		casacore::Float	rmMax,
		casacore::Float	maxPaErr = `1.0e30`,
		casacore::Float	sigma = `-1.0`,
		casacore::Float	rmFg = `0.0`,
		casacore::Bool	showProgress = `false`
	)

This function applies a traditional (i.e.

non-Fourier) Rotation Measure algorithm (Leahy et al, A&A, 156, 234) approach. For the RM images you must get the shape and CoordinateSYstem from function rotationMeasureShape. For the position angle images, use function singleStokesShape. Null pointer ImageInterface objects are not accessed so you can select which output images you want. Any output images not masked will be given a mask. The position angles are all in degrees. The RM images in rad/m/m. ImageInfo and Units, are copied to the output. MiscInfo and history are not. You specify which axis houses the frequencies, the noise level of Q and U if you know it (by default it is worked out for you) for error images, the value of the foreground RM if you know it (helps for unwinding ambiguity), the absolute maximum RM it should solve for, and the maximum error in the position angle that should be allowed. The state of the plotter should be set by the caller (e.g. character size, number of plots in x and y etc).

casacore::IPosition casa::ImagePolarimetry::rotationMeasureShape	(	casacore::CoordinateSystem &	cSys,
		casacore::Int &	frequencyAxis,
		casacore::Int &	stokesAxis,
		casacore::LogIO &	os,
		casacore::Int	spectralAxis = `-1`
	)		const

This function is used in concert with the rotationMeasure function.

It tells you what the shape of the output RM image should be, and gives you its CoordinateSystem. Because the ImagePolarimetry construction image may house the frequencies coordinate description in a Spectral, Tabular or Linear coordinate, you may explicitly specify which axis is the Spectral axis (spectralAxis). By default, it tries to find the SpectralCoordinate. If there is none, it will look for Tabular or Linear coordinates with a "FREQ" label. It returns to you the frequencyAxis (i.e. the one it is concluded houses the frequency spectrum) and the stokesAxis that it finds.

casacore::IPosition casa::ImagePolarimetry::shape ( ) const

inline

Get the shape of the construction image.

Definition at line 144 of file ImagePolarimetry.h.

References _image.

casacore::Float casa::ImagePolarimetry::sigma ( casacore::Float clip = 10.0 )

Get the best estimate of the statistical noise.

This gives you the standard deviation with outliers from the mean clipped first. The idea is to not be confused by source or dynamic range issues. Generally Stokes V is empty of sources (not always), then Q and U are generally less bright than I. So this function first tries V, then Q and U and lastly I to give you its noise estimate

static casacore::ImageExpr<casacore::Float> casa::ImagePolarimetry::sigmaDepolarizationRatio	(	const casacore::ImageInterface< casacore::Float > &	im1,
		const casacore::ImageInterface< casacore::Float > &	im2,
		casacore::Bool	debias,
		casacore::Float	clip = `10.0`,
		casacore::Float	sigma = `-1.0`
	)

static

casacore::ImageExpr<casacore::Float> casa::ImagePolarimetry::sigmaFracLinPol	(	casacore::Float	clip = `10.0`,
		casacore::Float	sigma = `-1.0`
	)

casacore::ImageExpr<casacore::Float> casa::ImagePolarimetry::sigmaFracTotPol	(	casacore::Float	clip = `10.0`,
		casacore::Float	sigma = `-1.0`
	)

casacore::Float casa::ImagePolarimetry::sigmaLinPolInt	(	casacore::Float	clip = `10.0`,
		casacore::Float	sigma = `-1.0`
	)

Get the linearly polarized intensity image and its standard deviation.

If wish to debias the image, you can either provide sigma (the standard deviation of the termal noise) or if sigma is non-positive, it will be worked out for you with a clipped mean algorithm.

casacore::ImageExpr<casacore::Float> casa::ImagePolarimetry::sigmaLinPolPosAng	(	casacore::Bool	radians,
		casacore::Float	clip = `10.0`,
		casacore::Float	sigma = `-1.0`
	)

casacore::Float casa::ImagePolarimetry::sigmaStokes	(	ImagePolarimetry::StokesTypes	index,
		casacore::Float	clip = `10.0`
	)

casacore::Float casa::ImagePolarimetry::sigmaStokesI ( casacore::Float clip = 10.0 )

casacore::Float casa::ImagePolarimetry::sigmaStokesQ ( casacore::Float clip = 10.0 )

casacore::Float casa::ImagePolarimetry::sigmaStokesU ( casacore::Float clip = 10.0 )

casacore::Float casa::ImagePolarimetry::sigmaStokesV ( casacore::Float clip = 10.0 )

casacore::Float casa::ImagePolarimetry::sigmaTotPolInt	(	casacore::Float	clip = `10.0`,
		casacore::Float	sigma = `-1.0`
	)

casacore::IPosition casa::ImagePolarimetry::singleStokesShape	(	casacore::CoordinateSystem &	cSys,
		casacore::Stokes::StokesTypes	type
	)		const

Get the shape and casacore::CoordinateSystem of an image for a single Stokes pixel.

Thus, if the construction image shape was [10,10,4,20] where axis 2 (shape 4) is the casacore::Stokes axis, this function would return [10,10,1,20] Specify the type of casacore::Stokes pixel you want.

casacore::ImageExpr<casacore::Float> casa::ImagePolarimetry::stokes ( ImagePolarimetry::StokesTypes index ) const

Get the specified casacore::Stokes image and the standard deviation of the image.