tcs_photometry::Photometry Class Reference

Public Types

• typedef ltl::MArray< float, 2 > MImage
• typedef ltl::MArray< char, 2 > MMask
• typedef std::list< Object * > ObjectList

Public Member Functions

• Photometry (const PhotometryParams &pp)
• void SetParams (const PhotometryParams &pp)
• MImage copy_square (const MImage &A, const int minx, const int maxx, const int miny, const int maxy)
• int subtract_background_fit (MImage &I)
• int subtract_background_fit_annulus (MImage &I)
• ObjectList find_stars (const MImage &I)
• int kron_aperture_phot (const MImage &I, const Object &o, PhotData &pd, AperturePhotResults &res)
• int fixed_aperture_phot (const MImage &I, const Object &o, PhotData &pd, AperturePhotResults &res)
• int fit_bivariate_gaussian (MImage &A, const float x, const float y, const int radius, FitPars &pd)

Protected Member Functions

• int aperture_phot (const MImage &Image, const float x, const float y, const float aper, const float sky1, const float sky2, PhotData &pd, AperturePhotResults &res)
• list< Object * > assemble (MMask &M, const MImage &I)
• void mark_pixels (Object &obj, const int x, const int y, MMask &M, const MImage &I)
• float integrate_soft_e_mask_fixed (const MImage &I, const float sky, float xc, float yc, float ap, const int subsample, float *area)
• Photometry::MImage elliptical_mask (const MImage &I, const float xc, const float yc, const float a1, const float b1, const float pa)
• Photometry::MImage elliptical_annulus_mask (const MImage &I, const float xc, const float yc, const float a1, const float b1, const float a2, const float b2, const float pa)
• bool check_variance (const MImage &I)

Protected Attributes

• PhotometryParams pp_

  parameter block for the photometry routines
  

• double bg_
• double sigma_bg_

  background value and stddev.
  

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Detailed Description

Object Detection and Photometry Class

Possible usage includes:

• Fit a global background polynomial to the whole image and subtract
• Subtract the local background around our guide star using the background signal in an annulus around the star. A first-order surface is fitted to the annulus and subtracted.
• Detect sources in the rectangular region around the guide star. Sources are defined as a minimum number of adjacent pixels with flux above some factor times the background rms noise.
• For each source
• Measure the source's parameters
• Perform Kron-aperture photometry on the source
• Fit a PSF model to the source

For examples of usage see testphot.cpp

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Member Typedef Documentation

typedef ltl::MArray<float,2> tcs_photometry::Photometry::MImage

typedef ltl::MArray<char, 2> tcs_photometry::Photometry::MMask

typedef std::list<Object*> tcs_photometry::Photometry::ObjectList

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Constructor & Destructor Documentation

tcs_photometry::Photometry::Photometry

(

const PhotometryParams &

pp

)

[inline]

References bg_, and sigma_bg_.

---

Member Function Documentation

void tcs_photometry::Photometry::SetParams

(

const PhotometryParams &

pp

)

[inline]

References pp_.

Referenced by tcs_photometry::GuiderPhot::SetParams().

MImage tcs_photometry::Photometry::copy_square	(	const MImage &	A,
		const int	minx,
		const int	maxx,
		const int	miny,
		const int	maxy
	)

Copy out a rectangular region out of an image. The new image retains the index ranges corresponding to the coordinates within the original image.

Copy out a square region containing the circle centered at x,y with radius. The new image retains the index ranges corresponding to the coordinates within the original image.

Referenced by main().

int tcs_photometry::Photometry::subtract_background_fit

(

MImage &

I

)

subtract the background from an image using a k-th order surface fit to the image values. Also computes the RMS within the image.

References tcs_photometry::PhotometryParams::bgorder_, tcs_photometry::PhotometryParams::nanval_, and pp_.

Referenced by main().

int tcs_photometry::Photometry::subtract_background_fit_annulus

(

MImage &

I

)

subtract the background from an image using a 2nd order surface fit to the image values in an annulus. Also computes the RMS within that annulus.

subtract the background from an image using a first-order surface fit to the image values in an annulus. Also computes the RMS within that annulus.

References bg_, elliptical_annulus_mask(), pp_, sigma_bg_, tcs_photometry::PhotometryParams::sky_annulus_, and UNRELIABLE_BACKGROUND.

Referenced by main().

Photometry::ObjectList tcs_photometry::Photometry::find_stars

(

const MImage &

I

)

threshold the image at some level above the background noise, segment the resulting image mask and assemble Objects out of consecutive regions.

References assemble(), tcs_photometry::PhotometryParams::detect_sigma_, pp_, and sigma_bg_.

Referenced by main().

int tcs_photometry::Photometry::kron_aperture_phot	(	const MImage &	I,
		const Object &	o,
		PhotData &	pd,
		AperturePhotResults &	res
	)			[inline]

Photometry in Kron-like aperture (aperture size based on a constant times the intensity-weighted first moment of the image)

References aperture_phot(), tcs_photometry::Object::icx_, tcs_photometry::Object::icy_, tcs_photometry::Object::ir1_, tcs_photometry::PhotData::kron_aper_, tcs_photometry::PhotometryParams::kron_factor_, pp_, and tcs_photometry::PhotometryParams::sky_annulus_.

Referenced by main().

int tcs_photometry::Photometry::fixed_aperture_phot	(	const MImage &	I,
		const Object &	o,
		PhotData &	pd,
		AperturePhotResults &	res
	)			[inline]

Photometry in Kron-like aperture (aperture size based on a constant times the intensity-weighted first moment of the image)

References aperture_phot(), tcs_photometry::PhotData::fixed_aper_, tcs_photometry::Object::icx_, tcs_photometry::Object::icy_, pp_, and tcs_photometry::PhotometryParams::sky_annulus_.

Referenced by main().

int tcs_photometry::Photometry::fit_bivariate_gaussian	(	MImage &	A,
		const float	x,
		const float	y,
		const int	radius,
		FitPars &	fp
	)

Fit a bivariate Gaussian ellipsoid to the image of a source

References a, b, bg_, tcs_photometry::FitPars::chi2_, tcs_photometry::FitPars::dflux_, tcs_photometry::FitPars::dm_, tcs_photometry::FitPars::e_gauss_par_, FIT_RADIUS_TOO_BIG, tcs_photometry::FitPars::flux_, tcs_photometry::FitPars::gauss_par_, tcs_photometry::FitPars::m_, tcs_photometry::PhotometryParams::magzero_, MAX_GAUSSFIT_RADIUS, OBJECT_AT_IMAGE_BORDER, and pp_.

Referenced by main().

int tcs_photometry::Photometry::aperture_phot	(	const MImage &	Image,
		const float	x,
		const float	y,
		const float	aper,
		const float	sky1,
		const float	sky2,
		PhotData &	pd,
		AperturePhotResults &	res
	)			[protected]

Circular aperture photometry Object center: x,y Aperture radius in pixels: aper Beginning and end of sky annulus: sky1, sky2

References check_variance(), tcs_photometry::AperturePhotResults::df_, tcs_photometry::AperturePhotResults::dm_, tcs_photometry::AperturePhotResults::dsky_, elliptical_annulus_mask(), tcs_photometry::AperturePhotResults::f_, tcs_photometry::PhotometryParams::gain_, integrate_soft_e_mask_fixed(), tcs_photometry::AperturePhotResults::m_, tcs_photometry::PhotometryParams::magzero_, OBJECT_AT_IMAGE_BORDER, OBJECT_IN_BAD_IMAGE_REGION, pp_, tcs_photometry::PhotData::setflag(), and tcs_photometry::AperturePhotResults::sky_.

Referenced by fixed_aperture_phot(), and kron_aperture_phot().

Photometry::ObjectList tcs_photometry::Photometry::assemble	(	MMask &	M,
		const MImage &	I
	)			[protected]

segment the image into consecutive regions above threshold

References tcs_photometry::Object::evaluate(), tcs_photometry::Object::icx_, tcs_photometry::Object::icy_, tcs_photometry::PhotometryParams::magzero_, mark_pixels(), tcs_photometry::PhotometryParams::maxsize_, tcs_photometry::PhotometryParams::npixmin_, tcs_photometry::Object::pixnum(), pp_, and tcs_photometry::PhotometryParams::saturation_.

Referenced by find_stars().

void tcs_photometry::Photometry::mark_pixels	(	Object &	obj,
		const int	x,
		const int	y,
		MMask &	M,
		const MImage &	I
	)			[protected]

recursively add pixels surrounding a pixel (x,y) to an object if they are flagged in the mask as lying above threshold

References tcs_photometry::Object::addpixel(), tcs_photometry::PhotometryParams::maxsize_, tcs_photometry::Object::pixnum(), and pp_.

Referenced by assemble().

float tcs_photometry::Photometry::integrate_soft_e_mask_fixed	(	const MImage &	I,
		const float	sky,
		float	xc,
		float	yc,
		float	ap,
		const int	subsample,
		float *	area
	)			[protected]

Integrate the flux within an elliptical aperture by subsampling the image and computing the intersection of the ellipse with the subsampled pixels.

Referenced by aperture_phot().

Photometry::MImage tcs_photometry::Photometry::elliptical_mask	(	const MImage &	I,
		const float	xc,
		const float	yc,
		const float	a1,
		const float	b1,
		const float	pa
	)			[protected]

Return an image multiplied by the characteristic function of an ellipse All pixels outside the ellipse will be set to zero, pixels within the ellipse will retain their values.

References tcs_photometry::PhotometryParams::nanval_, and pp_.

Photometry::MImage tcs_photometry::Photometry::elliptical_annulus_mask	(	const MImage &	I,
		const float	xc,
		const float	yc,
		const float	a1,
		const float	b1,
		const float	a2,
		const float	b2,
		const float	pa
	)			[protected]

Return an image multiplied by the characteristic function of an elliptical annulus. All pixels outside the annulus will be set to zero. Pixels within the annulus will retain their values.

References tcs_photometry::PhotometryParams::nanval_, and pp_.

Referenced by aperture_phot(), and subtract_background_fit_annulus().

bool tcs_photometry::Photometry::check_variance

(

const MImage &

I

)

[protected]

make sure the image looks OK by looking at variances ...

Referenced by aperture_phot().

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Field Documentation

PhotometryParams tcs_photometry::Photometry::pp_ [protected]

Referenced by aperture_phot(), assemble(), elliptical_annulus_mask(), elliptical_mask(), find_stars(), fit_bivariate_gaussian(), fixed_aperture_phot(), kron_aperture_phot(), mark_pixels(), SetParams(), subtract_background_fit(), and subtract_background_fit_annulus().

double tcs_photometry::Photometry::bg_ [protected]

Referenced by fit_bivariate_gaussian(), Photometry(), and subtract_background_fit_annulus().

double tcs_photometry::Photometry::sigma_bg_ [protected]

Referenced by find_stars(), Photometry(), and subtract_background_fit_annulus().