lsst::afw::detection::Threshold Class Reference

A Threshold is used to pass a threshold value to detection algorithms. More...

#include <Threshold.h>

Public Types
enum	ThresholdType {   VALUE , BITMASK , STDEV , VARIANCE ,   PIXEL_STDEV }
	Types of threshold: More...

Public Member Functions
	Threshold (double const value, ThresholdType const type=VALUE, bool const polarity=true, double const includeMultiplier=1.0)
	Threshold constructor.
	~Threshold () noexcept=default
	Threshold (Threshold const &) noexcept=default
	Threshold (Threshold &&) noexcept=default
Threshold &	operator= (Threshold const &) noexcept=default
Threshold &	operator= (Threshold &&) noexcept=default
ThresholdType	getType () const noexcept
	return type of threshold
double	getValue (const double param=-1) const
	return value of threshold, to be interpreted via type
template<typename ImageT>
double	getValue (ImageT const &image) const
	return value of threshold by interrogating the image, if required
bool	getPolarity () const noexcept
	return Threshold's polarity
void	setPolarity (bool const polarity) noexcept
	set Threshold's polarity
double	getIncludeMultiplier () const noexcept
	return includeMultiplier
void	setIncludeMultiplier (double const includeMultiplier)
	set includeMultiplier

Static Public Member Functions
static ThresholdType	parseTypeString (std::string const &typeStr)
static std::string	getTypeString (ThresholdType const &type)

Detailed Description

A Threshold is used to pass a threshold value to detection algorithms.

The threshold may be a simple value (type == VALUE), or in units of the image standard deviation. Alternatively you may specify that you'll provide the standard deviation (type == STDEV) or variance (type == VARIANCE)

Note that the constructor is not declared explicit, so you may pass a bare threshold, and it'll be interpreted as a VALUE.

Definition at line 43 of file Threshold.h.

Member Enumeration Documentation

ThresholdType

enum lsst::afw::detection::Threshold::ThresholdType

Types of threshold:

Enumerator
VALUE	Use pixel value.
BITMASK	Use (pixels & (given mask))
STDEV	Use number of sigma given s.d.
VARIANCE	Use number of sigma given variance.
PIXEL_STDEV	Use number of sigma given per-pixel s.d.

Definition at line 46 of file Threshold.h.

                       {
        VALUE,       
        BITMASK,     
        STDEV,       
        VARIANCE,    
        PIXEL_STDEV  
    };

Constructor & Destructor Documentation

Threshold() [1/3]

lsst::afw::detection::Threshold::Threshold ( double const value, ThresholdType const type = VALUE, bool const polarity = true, double const includeMultiplier = 1.0 )

inline

Threshold constructor.

Parameters

value	desired threshold value
type	interpretation of type
polarity	search pixel above threshold? (useful for -ve thresholds)
includeMultiplier	threshold multiplier for inclusion in FootprintSet

Definition at line 57 of file Threshold.h.

            : _value(value), _type(type), _polarity(polarity), _includeMultiplier(includeMultiplier) {}

~Threshold()

lsst::afw::detection::Threshold::~Threshold ( )

defaultnoexcept

Threshold() [2/3]

lsst::afw::detection::Threshold::Threshold ( Threshold const & )

defaultnoexcept

Threshold() [3/3]

lsst::afw::detection::Threshold::Threshold ( Threshold && )

defaultnoexcept

Member Function Documentation

getIncludeMultiplier()

double lsst::afw::detection::Threshold::getIncludeMultiplier ( ) const

inlinenoexcept

return includeMultiplier

Definition at line 100 of file Threshold.h.

{ return _includeMultiplier; }

getPolarity()

bool lsst::afw::detection::Threshold::getPolarity ( ) const

inlinenoexcept

return Threshold's polarity

Definition at line 92 of file Threshold.h.

{ return _polarity; }

getType()

ThresholdType lsst::afw::detection::Threshold::getType ( ) const

inlinenoexcept

return type of threshold

Definition at line 71 of file Threshold.h.

{ return _type; }

getTypeString()

std::string lsst::afw::detection::Threshold::getTypeString ( ThresholdType const & type )

static

Definition at line 54 of file Threshold.cc.

                                                            {
    if (type == VALUE) {
        return "value";
    } else if (type == STDEV) {
        return "stdev";
    } else if (type == VARIANCE) {
        return "variance";
    } else {
        throw LSST_EXCEPT(lsst::pex::exceptions::InvalidParameterError,
                          (boost::format("Unsopported Threshold type: %d") % type).str());
    }
}

getValue() [1/2]

double lsst::afw::detection::Threshold::getValue

(

const double

param = -1

)

const

return value of threshold, to be interpreted via type

Parameters

param

value of variance/stdev if needed

Returns

value of threshold

Definition at line 67 of file Threshold.cc.

                                                   {
    switch (_type) {
        case STDEV:
            if (param <= 0) {
                throw LSST_EXCEPT(lsst::pex::exceptions::InvalidParameterError,
                                  (boost::format("St. dev. must be > 0: %g") % param).str());
            }
            return _value * param;
        case VALUE:
        case BITMASK:
        case PIXEL_STDEV:
            return _value;
        case VARIANCE:
            if (param <= 0) {
                throw LSST_EXCEPT(lsst::pex::exceptions::InvalidParameterError,
                                  (boost::format("Variance must be > 0: %g") % param).str());
            }
            return _value * std::sqrt(param);
        default:
            throw LSST_EXCEPT(lsst::pex::exceptions::InvalidParameterError,
                              (boost::format("Unsupported type: %d") % _type).str());
    }
}

getValue() [2/2]

template<typename ImageT>

double lsst::afw::detection::Threshold::getValue

(

ImageT const &

image

)

const

return value of threshold by interrogating the image, if required

Parameters

image

Image to interrogate, if threshold type demands

Returns

value of threshold

Definition at line 92 of file Threshold.cc.

                                                    {
    double param = -1;  // Parameter for getValue()
    if (_type == STDEV || _type == VARIANCE) {
        math::Statistics stats = math::makeStatistics(image, math::STDEVCLIP);
        double const sd = stats.getValue(math::STDEVCLIP);
 
        LOGL_DEBUG("lsst.afw.detection.threshold", "St. Dev = %g", sd);
 
        if (_type == VARIANCE) {
            param = sd * sd;
        } else {
            param = sd;
        }
    }
    return getValue(param);
}

operator=() [1/2]

Threshold & lsst::afw::detection::Threshold::operator= ( Threshold && )

defaultnoexcept

operator=() [2/2]

Threshold & lsst::afw::detection::Threshold::operator= ( Threshold const & )

defaultnoexcept

parseTypeString()

Threshold::ThresholdType lsst::afw::detection::Threshold::parseTypeString ( std::string const & typeStr )

static

Definition at line 37 of file Threshold.cc.

                                                                          {
    if (typeStr.compare("bitmask") == 0) {
        return Threshold::BITMASK;
    } else if (typeStr.compare("value") == 0) {
        return Threshold::VALUE;
    } else if (typeStr.compare("stdev") == 0) {
        return Threshold::STDEV;
    } else if (typeStr.compare("variance") == 0) {
        return Threshold::VARIANCE;
    } else if (typeStr.compare("pixel_stdev") == 0) {
        return Threshold::PIXEL_STDEV;
    } else {
        throw LSST_EXCEPT(lsst::pex::exceptions::InvalidParameterError,
                          (boost::format("Unsupported Threshold type: %s") % typeStr).str());
    }
}

setIncludeMultiplier()

void lsst::afw::detection::Threshold::setIncludeMultiplier ( double const includeMultiplier )

inline

set includeMultiplier

Parameters

includeMultiplier

desired multiplier

Definition at line 102 of file Threshold.h.

      {
        _includeMultiplier = includeMultiplier;
    }

setPolarity()

void lsst::afw::detection::Threshold::setPolarity ( bool const polarity )

inlinenoexcept

set Threshold's polarity

Parameters

polarity

desired polarity

Definition at line 94 of file Threshold.h.

                                {
        _polarity = polarity;
    }

---

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

• /j/snowflake/release/lsstsw/stack/lsst-scipipe-12.1.0/Linux/afw/g7ae74a0b1c+a25e60b391/include/lsst/afw/detection/Threshold.h
• /j/snowflake/release/lsstsw/stack/lsst-scipipe-12.1.0/Linux/afw/g7ae74a0b1c+a25e60b391/src/detection/Threshold.cc