ImageDifferenceTask¶
Python API summary¶
from lsst.pipe.tasks.imageDifference import ImageDifferenceTask
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class
ImageDifferenceTask(*args, **kwargs) Subtract an image from a template and measure the result
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- attributeconfig
Access configuration fields and retargetable subtasks.
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method
run(exposure=None, selectSources=None, templateExposure=None, templateSources=None, idFactory=None, calexpBackgroundExposure=None, subtractedExposure=None) PSF matches, subtract two images and perform detection on the difference image
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See also
See the ImageDifferenceTask API reference for complete details.
Retargetable subtasks¶
applyApCorr¶
- Default
- Field type
Subtask to apply aperture corrections
astrometer¶
- Default
lsst.meas.astrom.astrometry.AstrometryTask- Field type
astrometry task; used to match sources to reference objects, but not to fit a WCS
decorrelate¶
- Default
lsst.ip.diffim.imageDecorrelation.DecorrelateALKernelSpatialTask- Field type
Decorrelate effects of A&L kernel convolution on image difference, only if doSubtract is True. If this option is enabled, then detection.thresholdValue should be set to 5.0 (rather than the default of 5.5).
detection¶
- Default
- Field type
Low-threshold detection for final measurement
forcedMeasurement¶
- Default
- Field type
Subtask to force photometer PVI at diaSource location.
getTemplate¶
- Default
lsst.ip.diffim.getTemplate.GetCoaddAsTemplateTask- Field type
Subtask to retrieve template exposure and sources
measurement¶
- Default
lsst.ip.diffim.dipoleFitTask.DipoleFitTask- Field type
Enable updated dipole fitting method
register¶
- Default
- Field type
Task to enable image-to-image image registration (warping)
scaleVariance¶
- Default
lsst.meas.algorithms.scaleVariance.ScaleVarianceTask- Field type
Subtask to rescale the variance of the template to the statistically expected level
skySources¶
- Default
- Field type
Generate sky sources
sourceSelector¶
- Default
lsst.meas.algorithms.objectSizeStarSelector.ObjectSizeStarSelectorTask- Field type
Source selection algorithm
subtract¶
- Default
'al'- Field type
Single-selection
RegistryField- Choices
'al'lsst.ip.diffim.imagePsfMatch.ImagePsfMatchTask'zogy'lsst.ip.diffim.zogy.ZogyImagePsfMatchTask
Subtraction Algorithm
Configuration fields¶
coaddName¶
coadd name: typically one of deep, goodSeeing, or dcr
connections¶
- Data type
lsst.pipe.base.config.Connections- Field type
Configurations describing the connections of the PipelineTask to datatypes
controlRandomSeed¶
Random seed for shuffing the control sample
controlStepSize¶
What step size (every Nth one) to select a control sample from the kernelSources
convolveTemplate¶
Which image gets convolved (default = template)
diaSourceMatchRadius¶
Match radius (in arcseconds) for DiaSource to Source association
doAddCalexpBackground¶
Add background to calexp before processing it. Useful as ipDiffim does background matching.
doAddMetrics¶
Add columns to the source table to hold analysis metrics?
doApCorr¶
Run subtask to apply aperture corrections
doApplyFinalizedPsf¶
Whether to apply finalized psf models and aperture correction map.
doDebugRegister¶
Writing debugging data for doUseRegister
doDecorrelation¶
Perform diffim decorrelation to undo pixel correlation due to A&L kernel convolution (AL only)? If True, also update the diffim PSF.
doDetection¶
Detect sources?
doDipoleFitting¶
Measure dipoles using new algorithm?
doForcedMeasurement¶
Force photometer diaSource locations on PVI?
doMatchSources¶
Match diaSources with input calexp sources and ref catalog sources
doMeasurement¶
Measure diaSources?
doMerge¶
Merge positive and negative diaSources with grow radius set by growFootprint
doPreConvolve¶
Not in use. Superseded by useScoreImageDetection. Deprecated: This option superseded by useScoreImageDetection. Will be removed after v22.
doScaleDiffimVariance¶
Scale variance of the diffim before PSF matching. You may do either this or template variance scaling, or neither. (Doing both is a waste of CPU.)
doScaleTemplateVariance¶
Scale variance of the template before PSF matching
doSelectDcrCatalog¶
Select stars of extreme color as part of the control sample (AL only)
doSelectSources¶
Select stars to use for kernel fitting (AL only)
doSelectVariableCatalog¶
Select stars that are variable to be part of the control sample (AL only)
doSkySources¶
Generate sky sources?
doSpatiallyVarying¶
Perform A&L decorrelation on a grid across the image in order to allow for spatial variations. Zogy does not use this option.
doSubtract¶
Compute subtracted exposure?
doUseRegister¶
Re-compute astrometry on the template. Use image-to-image registration to align template with science image (AL only).
doWriteMatchedExp¶
Write warped and PSF-matched template coadd exposure?
doWriteScoreExp¶
Write AL likelihood or Zogy score exposure?
doWriteSources¶
Write sources?
doWriteSubtractedExp¶
Write difference exposure (AL and Zogy) ?
doWriteWarpedExp¶
Write WCS, warped template coadd exposure?
growFootprint¶
Grow positive and negative footprints by this amount before merging
kernelSourcesFromRef¶
Select sources to measure kernel from reference catalog if True, template if false
refObjLoader¶
- Data type
lsst.meas.algorithms.loadReferenceObjects.LoadReferenceObjectsConfig- Field type
reference object loader
requiredTemplateFraction¶
Do not attempt to run task if template covers less than this fraction of pixels.Setting to 0 will always attempt image subtraction
saveLogOutput¶
Flag to enable/disable saving of log output for a task, enabled by default.
saveMetadata¶
Flag to enable/disable metadata saving for a task, enabled by default.
templateSipOrder¶
Sip Order for fitting the Template Wcs (default is too high, overfitting)
useGaussianForPreConvolution¶
Use a simple gaussian PSF model for pre-convolution (oherwise use exposure PSF)? (AL and if useScoreImageDetection=True only)
useScoreImageDetection¶
Calculate the pre-convolved AL likelihood or the Zogy score image. Use it for source detection (if doDetection=True).
Python API reference¶
lsst.pipe.tasks.imageDifference Module¶
Classes¶
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Config for ImageDifferenceTask. |
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Subtract an image from a template and measure the result. |