ImageDifferenceTask

Python API summary

from lsst.pipe.tasks.imageDifference import ImageDifferenceTask
classImageDifferenceTask(butler=None, **kwargs)

Subtract an image from a template and measure the result...

attributeconfig

Access configuration fields and retargetable subtasks.

methodrun(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...

methodrunDataRef(sensorRef, templateIdList=None)

Subtract an image from a template coadd and measure the result...

See also

See the ImageDifferenceTask API reference for complete details.

Retargetable subtasks

applyApCorr

Default

lsst.meas.base.applyApCorr.ApplyApCorrTask

Field type

ConfigurableField

Subtask to apply aperture corrections

astrometer

Default

lsst.meas.astrom.astrometry.AstrometryTask

Field type

ConfigurableField

astrometry task; used to match sources to reference objects, but not to fit a WCS

decorrelate

Default

lsst.ip.diffim.imageDecorrelation.DecorrelateALKernelSpatialTask

Field type

ConfigurableField

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

lsst.meas.algorithms.detection.SourceDetectionTask

Field type

ConfigurableField

Low-threshold detection for final measurement

forcedMeasurement

Default

lsst.meas.base.forcedMeasurement.ForcedMeasurementTask

Field type

ConfigurableField

Subtask to force photometer PVI at diaSource location.

getTemplate

Default

lsst.ip.diffim.getTemplate.GetCoaddAsTemplateTask

Field type

ConfigurableField

Subtask to retrieve template exposure and sources

measurement

Default

lsst.ip.diffim.dipoleFitTask.DipoleFitTask

Field type

ConfigurableField

Enable updated dipole fitting method

refObjLoader

Default

lsst.meas.algorithms.loadIndexedReferenceObjects.LoadIndexedReferenceObjectsTask

Field type

ConfigurableField

reference object loader

register

Default

lsst.pipe.tasks.registerImage.RegisterTask

Field type

ConfigurableField

Task to enable image-to-image image registration (warping)

scaleVariance

Default

lsst.meas.algorithms.scaleVariance.ScaleVarianceTask

Field type

ConfigurableField

Subtask to rescale the variance of the template to the statistically expected level

skySources

Default

lsst.meas.algorithms.skyObjects.SkyObjectsTask

Field type

ConfigurableField

Generate sky sources

sourceSelector

Default

lsst.meas.algorithms.objectSizeStarSelector.ObjectSizeStarSelectorTask

Field type

ConfigurableField

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

Default
'deep'
Field type

str Field

coadd name: typically one of deep, goodSeeing, or dcr

connections

Data type

lsst.pipe.base.config.Connections

Field type

ConfigField

Configurations describing the connections of the PipelineTask to datatypes

controlRandomSeed

Default
10
Field type

int Field

Random seed for shuffing the control sample

controlStepSize

Default
5
Field type

int Field

What step size (every Nth one) to select a control sample from the kernelSources

convolveTemplate

Default
True
Field type

bool Field

Which image gets convolved (default = template)

diaSourceMatchRadius

Default
0.5
Field type

float Field

Match radius (in arcseconds) for DiaSource to Source association

doAddCalexpBackground

Default
False
Field type

bool Field

Add background to calexp before processing it. Useful as ipDiffim does background matching.

doAddMetrics

Default
False
Field type

bool Field

Add columns to the source table to hold analysis metrics?

doApCorr

Default
True
Field type

bool Field

Run subtask to apply aperture corrections

doApplyFinalizedPsf

Default
False
Field type

bool Field

Whether to apply finalized psf models and aperture correction map.

doDebugRegister

Default
False
Field type

bool Field

Writing debugging data for doUseRegister

doDecorrelation

Default
True
Field type

bool Field

Perform diffim decorrelation to undo pixel correlation due to A&L kernel convolution (AL only)? If True, also update the diffim PSF.

doDetection

Default
True
Field type

bool Field

Detect sources?

doDipoleFitting

Default
True
Field type

bool Field

Measure dipoles using new algorithm?

doForcedMeasurement

Default
True
Field type

bool Field

Force photometer diaSource locations on PVI?

doMatchSources

Default
False
Field type

bool Field

Match diaSources with input calexp sources and ref catalog sources

doMeasurement

Default
True
Field type

bool Field

Measure diaSources?

doMerge

Default
True
Field type

bool Field

Merge positive and negative diaSources with grow radius set by growFootprint

doPreConvolve

Default
False
Field type

bool Field

Not in use. Superseded by useScoreImageDetection. Deprecated: This option superseded by useScoreImageDetection. Will be removed after v22.

doScaleDiffimVariance

Default
True
Field type

bool Field

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

Default
False
Field type

bool Field

Scale variance of the template before PSF matching

doSelectDcrCatalog

Default
False
Field type

bool Field

Select stars of extreme color as part of the control sample (AL only)

doSelectSources

Default
False
Field type

bool Field

Select stars to use for kernel fitting (AL only)

doSelectVariableCatalog

Default
False
Field type

bool Field

Select stars that are variable to be part of the control sample (AL only)

doSkySources

Default
False
Field type

bool Field

Generate sky sources?

doSpatiallyVarying

Default
False
Field type

bool Field

Perform A&L decorrelation on a grid across the image in order to allow for spatial variations. Zogy does not use this option.

doSubtract

Default
True
Field type

bool Field

Compute subtracted exposure?

doUseRegister

Default
False
Field type

bool Field

Re-compute astrometry on the template. Use image-to-image registration to align template with science image (AL only).

doWriteMatchedExp

Default
False
Field type

bool Field

Write warped and PSF-matched template coadd exposure?

doWriteScoreExp

Default
False
Field type

bool Field

Write AL likelihood or Zogy score exposure?

doWriteSources

Default
True
Field type

bool Field

Write sources?

doWriteSubtractedExp

Default
True
Field type

bool Field

Write difference exposure (AL and Zogy) ?

doWriteWarpedExp

Default
False
Field type

bool Field

Write WCS, warped template coadd exposure?

growFootprint

Default
2
Field type

int Field

Grow positive and negative footprints by this amount before merging

kernelSourcesFromRef

Default
False
Field type

bool Field

Select sources to measure kernel from reference catalog if True, template if false

requiredTemplateFraction

Default
0.1
Field type

float Field

Do not attempt to run task if template covers less than this fraction of pixels.Setting to 0 will always attempt image subtraction

saveLogOutput

Default
True
Field type

bool Field

Flag to enable/disable saving of log output for a task, enabled by default.

saveMetadata

Default
True
Field type

bool Field

Flag to enable/disable metadata saving for a task, enabled by default.

templateSipOrder

Default
2
Field type

int Field

Sip Order for fitting the Template Wcs (default is too high, overfitting)

useGaussianForPreConvolution

Default
False
Field type

bool Field

Use a simple gaussian PSF model for pre-convolution (oherwise use exposure PSF)? (AL and if useScoreImageDetection=True only)

useScoreImageDetection

Default
False
Field type

bool Field

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

ImageDifferenceConfig(*args, **kw)

Config for ImageDifferenceTask

ImageDifferenceTask([butler])

Subtract an image from a template and measure the result

Class Inheritance Diagram

Inheritance diagram of lsst.pipe.tasks.imageDifference.ImageDifferenceConfig, lsst.pipe.tasks.imageDifference.ImageDifferenceTask