Functions | |
| record_from_obs_info (obs_info, instrument, visit, universe) | |
| get_difference_image_provenance (image, attribute, connection, dataId) | |
| getKernelCenterDisplacement (kernel, x, y, image=None) | |
| getPsfFwhm (psf, average=True, position=None) | |
| float | evaluateMeanPsfFwhm (afwImage.Exposure exposure, float fwhmExposureBuffer, int fwhmExposureGrid) |
| afwImage.ImageD | computeAveragePsf (afwImage.Exposure exposure, float psfExposureBuffer, int psfExposureGrid) |
| computeRobustStatistics (image, mask, statsCtrl, statistic=afwMath.MEANCLIP) | |
| computePSFNoiseEquivalentArea (psf) | |
| angleMean (angles) | |
| evaluateMaskFraction (mask, maskPlane) | |
| computeDifferenceImageMetrics (science, difference, stars, sky_sources=None) | |
| populate_sattle_visit_cache (visit_info, historical=False) | |
| checkMask (mask, sources, excludeMaskPlanes) | |
| setSourceFootprints (sources, kernelSize) | |
Variables | |
| _LOG = getLogger(__name__) | |
Detailed Description
Support utilities for Measuring sources
Function Documentation
◆ angleMean()
| angleMean | ( | angles | ) |
◆ checkMask()
| checkMask | ( | mask, | |
| sources, | |||
| excludeMaskPlanes ) |
Exclude sources that have masked pixels in their footprints.
Parameters
----------
mask : `lsst.afw.image.Mask`
The image mask plane to use to reject sources
based on the location of their centroid on the ccd.
sources : `lsst.afw.table.SourceCatalog`
The source catalog to evaluate.
excludeMaskPlanes : `list` of `str`
List of the names of the mask planes to exclude.
Returns
-------
good : `numpy.ndarray` of `bool`
Array indicating whether each source in the catalog should be
kept (True) or rejected (False) based on the value of the
mask plane at its location.
◆ computeAveragePsf()
| afwImage.ImageD computeAveragePsf | ( | afwImage.Exposure | exposure, |
| float | psfExposureBuffer, | ||
| int | psfExposureGrid ) |
Get the average PSF by evaluating it on a grid within an exposure.
Parameters
----------
exposure : `~lsst.afw.image.Exposure`
The exposure for which the average PSF is to be computed.
The exposure must contain a `psf` attribute.
psfExposureBuffer : `float`
Fractional buffer margin to be left out of all sides of the image
during the construction of the grid to compute average PSF in an
exposure.
psfExposureGrid : `int`
Grid size to compute the average PSF in an exposure.
Returns
-------
psfImage : `~lsst.afw.image.Image`
The average PSF across the exposure.
Raises
------
ValueError
Raised if the PSF cannot be computed at any of the grid points.
See Also
--------
`evaluateMeanPsfFwhm`
◆ computeDifferenceImageMetrics()
| computeDifferenceImageMetrics | ( | science, | |
| difference, | |||
| stars, | |||
| sky_sources = None ) |
Compute quality metrics (saved to the task metadata) on the
difference image, at the locations of detected stars on the science
image. This restricts the metric to locations that should be
well-subtracted.
Parameters
----------
science : `lsst.afw.image.ExposureF`
Science exposure that was subtracted.
difference : `lsst.afw.image.ExposureF`
Result of subtracting template and science.
stars : `lsst.afw.table.SourceCatalog`
Good calibration sources detected on science image; these
footprints are what the metrics are computed on.
Returns
-------
metrics : `lsst.pipe.base.Struct`
``differenceFootprintRatioMean`` : `float`
Mean of the ratio of the absolute value of the difference image
(with the mean absolute value of the sky regions on the difference
image removed) to the science image, computed in the footprints
of stars detected on the science image (the sums below are of the
pixels in each star or sky footprint):
:math:`\mathrm{mean}_{footprints}((\sum |difference| -
\mathrm{mean}(\sum |difference_{sky}|)) / \sum science)`
``differenceFootprintRatioStdev`` : `float`
Standard Deviation across footprints of the above ratio.
``differenceFootprintSkyRatioMean`` : `float`
Mean of the ratio of the absolute value of sky source regions on
the difference image to the science image (the sum below is of the
pixels in each sky source footprint):
:math:`\mathrm{mean}_{footprints}(\sum |difference_{sky}| / \sum science_{sky})`
``differenceFootprintSkyRatioStdev`` : `float`
Standard Deivation across footprints of the above sky ratio.
◆ computePSFNoiseEquivalentArea()
| computePSFNoiseEquivalentArea | ( | psf | ) |
◆ computeRobustStatistics()
| computeRobustStatistics | ( | image, | |
| mask, | |||
| statsCtrl, | |||
| statistic = afwMath.MEANCLIP ) |
Calculate a robust mean of the variance plane of an exposure.
Parameters
----------
image : `lsst.afw.image.Image`
Image or variance plane of an exposure to evaluate.
mask : `lsst.afw.image.Mask`
Mask plane to use for excluding pixels.
statsCtrl : `lsst.afw.math.StatisticsControl`
Statistics control object for configuring the calculation.
statistic : `lsst.afw.math.Property`, optional
The type of statistic to compute. Typical values are
``afwMath.MEANCLIP`` or ``afwMath.STDEVCLIP``.
Returns
-------
value : `float`
The result of the statistic calculated from the unflagged pixels.
◆ evaluateMaskFraction()
| evaluateMaskFraction | ( | mask, | |
| maskPlane ) |
Evaluate the fraction of masked pixels in a mask plane.
Parameters
----------
mask : `lsst.afw.image.Mask`
The mask to evaluate the fraction on
maskPlane : `str`
The particular mask plane to evaluate the fraction
Returns
-------
value : `float`
The calculated fraction of masked pixels
◆ evaluateMeanPsfFwhm()
| float evaluateMeanPsfFwhm | ( | afwImage.Exposure | exposure, |
| float | fwhmExposureBuffer, | ||
| int | fwhmExposureGrid ) |
Get the mean PSF FWHM by evaluating it on a grid within an exposure.
Parameters
----------
exposure : `~lsst.afw.image.Exposure`
The exposure for which the mean FWHM of the PSF is to be computed.
The exposure must contain a `psf` attribute.
fwhmExposureBuffer : `float`
Fractional buffer margin to be left out of all sides of the image
during the construction of the grid to compute mean PSF FWHM in an
exposure.
fwhmExposureGrid : `int`
Grid size to compute the average PSF FWHM in an exposure (pixels).
Returns
-------
meanFwhm : `float`
The mean PSF FWHM on the exposure.
Raises
------
ValueError
Raised if the PSF cannot be computed at any of the grid points.
See Also
--------
`getPsfFwhm`
`computeAveragePsf`
◆ get_difference_image_provenance()
| get_difference_image_provenance | ( | image, | |
| attribute, | |||
| connection, | |||
| dataId ) |
Get the PSF matching kernel or the template records of an input
difference image.
Parameters
----------
image : `lsst.images.DifferenceImage`
Input image read by a task in future mode.
attribute : {"kernel", "templates"}
Name of the attribute to get.
connection : `str`
Name of the input connection the image was read from.
dataId : `lsst.daf.butler.DataCoordinate`
Data ID of the quantum, for the error message.
Returns
-------
value : `lsst.images.convolution_kernels.ConvolutionKernel` or \
`list` [`lsst.images.DifferenceImageTemplateInfo`]
Value of the attribute.
Raises
------
lsst.pipe.base.InvalidQuantumError
Raised if the image does not have the attribute, which happens when
the input was written as a legacy Exposure and converted on read.
◆ getKernelCenterDisplacement()
| getKernelCenterDisplacement | ( | kernel, | |
| x, | |||
| y, | |||
| image = None ) |
Calculate the PSF matching kernel peak offset from the nominal
position.
Parameters
----------
kernel : `~lsst.afw.math.LinearCombinationKernel`
The PSF matching kernel to evaluate.
x : `float`
The x position on the detector to evaluate the kernel
y : `float`
The y position on the detector to evaluate the kernel
image : `~lsst.afw.image.ImageD`
The image to use as base for computing kernel pixel values
Returns
-------
kernel_sum : `float`
The sum of the kernel on the desired location
dx : `float`
The displacement of the kernel averaged peak, with respect to the
center of the extraction of the kernel
dy : `float`
The displacement of the kernel averaged peak, with respect to the
center of the extraction of the kernel
pos_angle: `float`
The position angle in detector coordinates of the displacement
length : `float`
The displacement module of the kernel centroid in pixel units
◆ getPsfFwhm()
| getPsfFwhm | ( | psf, | |
| average = True, | |||
| position = None ) |
Directly calculate the horizontal and vertical widths
of a PSF at half its maximum value.
Parameters
----------
psf : `~lsst.afw.detection.Psf`
Point spread function (PSF) to evaluate.
average : `bool`, optional
Set to return the average width over Y and X axes.
position : `~lsst.geom.Point2D`, optional
The position at which to evaluate the PSF. If `None`, then the
average position is used.
Returns
-------
psfSize : `float` | `tuple` [`float`]
The FWHM of the PSF computed at its average position.
Returns the widths along the Y and X axes,
or the average of the two if `average` is set.
See Also
--------
evaluateMeanPsfFwhm
◆ populate_sattle_visit_cache()
| populate_sattle_visit_cache | ( | visit_info, | |
| historical = False ) |
Populate a cache of predicted satellite positions in the sattle service.
Parameters
----------
visit_info: `lsst.afw.table.ExposureRecord.visitInfo`
Visit info for the science exposure being processed.
historical: `bool`
Set to True if observations are older than the current day.
Raises
------
requests.HTTPError
Raised if sattle call does not return success.
◆ record_from_obs_info()
| record_from_obs_info | ( | obs_info, | |
| instrument, | |||
| visit, | |||
| universe ) |
Build an ``exposure`` dimension record from an observation info.
Parameters
----------
obs_info : `astro_metadata_translator.ObservationInfo`
Observation info of an image that the image to be converted is
derived from.
instrument : `str`
Name of the instrument, usually from the quantum data ID.
visit : `int`
Id of the visit, usually from the quantum data ID. It is also used
as the id of the exposure.
universe : `lsst.daf.butler.DimensionUniverse`
Dimension universe that defines the record's schema, usually
``butlerQC.quantum.dataId.universe``.
Returns
-------
record : `lsst.daf.butler.DimensionRecord`
An ``exposure`` record holding the fields that `lsst.images` reads
when it converts a legacy image. Fields it does not read, such as
``dark_time`` and ``target_name``, are `None`.
Raises
------
ValueError
Raised if ``obs_info`` is `None`, which means the image it came from
was not in an `lsst.images` format.
Notes
-----
The instrument and the visit are passed separately because an
observation info does not carry them in the form the conversion needs:
its ``instrument`` is read from the legacy FITS header rather than from
the record, and its ``exposure_id`` is the id that the visit info held.
◆ setSourceFootprints()
| setSourceFootprints | ( | sources, | |
| kernelSize ) |
Add footprints of fixed size to a source catalog
Each source's footprint is replaced by a centered box of side
``2*kernelSize + 1`` pixels (always odd), preserving the brightest peak
of the original footprint.
Parameters
----------
sources : `lsst.afw.table.SourceCatalog`
The source catalog to add footprints to. Modified in place.
kernelSize : `int`
Width (in pixels) of the PSF-matching kernel. The footprint size is
``2*kernelSize + 1`` so that the kernel can be convolved across the
source without falling off the stamp.
Returns
-------
sources : `lsst.afw.table.SourceCatalog`
The input `sources` catalog that was modified in place,
returned for convenience.
Variable Documentation
◆ _LOG
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