LinearitySolveTask¶

LinearitySolveTask constructs a linearity correction model (a Linearizer) based on the results stored in the input photon transfer curve (PTC) dataset.

Processing summary¶

LinearitySolveTask runs these operations:

Convert the input exposure time/photodiode flux measurement to a proxy flux by fitting the low-flux end with a linear fit.
Perform fit against using the observed flux and this linear proxy flux (using either a spline or a polynomial).
Store the correction, such that the corrected flux is equal to the uncorrected flux + the linearity correction as a function of the uncorrected flux.

Python API summary¶

from lsst.cp.pipe.linearity import LinearitySolveTask

classLinearitySolveTask(*, config=None, log=None, initInputs=None, **kwargs): Fit the linearity from the PTC dataset...

attributeconfig: Access configuration fields and retargetable subtasks.

methodrun(inputPtc, dummy, camera, inputDims, inputPhotodiodeCorrection=None): Fit non-linearity to PTC data, returning the correct Linearizer object...

Retargetable subtasks¶

No subtasks.

Configuration fields¶

applyPhotodiodeCorrection¶

Default: False
Field type: bool Field

Calculate and apply a correction to the photodiode readings?

connections¶

Data type: lsst.pipe.base.config.Connections
Field type: ConfigField

Configurations describing the connections of the PipelineTask to datatypes

ignorePtcMask¶

Default: False
Field type: bool Field

Ignore the expIdMask set by the PTC solver?

linearityType¶

Default

'Squared'

Field type

str ChoiceField (optional)

Choices

'LookupTable': Create a lookup table solution.
'Polynomial': Create an arbitrary polynomial solution.
'Squared': Create a single order squared solution.
'Spline': Create a spline based solution.
'None': Create a dummy solution.
None: Field is optional

Type of linearizer to construct.

maxLinearAdu¶

Default: 20000.0
Field type: float Field

Maximum DN value to use to estimate linear term.

maxLookupTableAdu¶

Default: 262144
Field type: int Field

Maximum DN value for a LookupTable linearizer.

minLinearAdu¶

Default: 2000.0
Field type: float Field

Minimum DN value to use to estimate linear term.

nSigmaClipLinear¶

Default: 5.0
Field type: float Field

Maximum deviation from linear solution for Poissonian noise.

polynomialOrder¶

Default: 3
Field type: int Field

Degree of polynomial to fit.

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.

splineKnots¶

Default: 10
Field type: int Field

Number of spline knots to use in fit.

usePhotodiode¶

Default: False
Field type: bool Field

Use the photodiode info instead of the raw expTimes?

Debugging¶

linearFit: Display the linearity solution after the initial linear fit (bool)?
polyFit: Display the linearity solution after generating the polynomial fit (bool)?
splineFit: Display the linearity solution after generating the spline fit (bool)?
solution: Display the final linearity solution (bool)?

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