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 lowflux 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

class
LinearitySolveTask
(*, config=None, log=None, initInputs=None, **kwargs) Fit the linearity from the PTC dataset
...
 attributeconfig
Access configuration fields and retargetable subtasks.

method
run
(inputPtc, dummy, camera, inputDims, inputPhotodiodeCorrection=None) Fit nonlinearity to PTC data, returning the correct Linearizer object
...
See also
See the LinearitySolveTask
API reference for complete details.
Retargetable subtasks¶
No subtasks.
Configuration fields¶
applyPhotodiodeCorrection¶
Calculate and apply a correction to the photodiode readings?
connections¶
 Data type
lsst.pipe.base.config.LinearitySolveConfigConnections
 Field type
Configurations describing the connections of the PipelineTask to datatypes
ignorePtcMask¶
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¶
Maximum DN value to use to estimate linear term.
maxLookupTableAdu¶
Maximum DN value for a LookupTable linearizer.
minLinearAdu¶
Minimum DN value to use to estimate linear term.
nSigmaClipLinear¶
Maximum deviation from linear solution for Poissonian noise.
photodiodeCurrentScale¶
Scale factor to apply to photodiode current values for the CHARGE_SUM
integration method. Deprecated: This config has been moved to cpExtractPtcTask, and will be removed after v26.
photodiodeIntegrationMethod¶
 Default
'DIRECT_SUM'
 Field type
str
ChoiceField
(optional) Choices
'DIRECT_SUM'
Use numpy’s trapz integrator on all photodiode readout entries
'TRIMMED_SUM'
Use numpy’s trapz integrator, clipping the leading and trailing entries, which are nominally at zero baseline level.
'CHARGE_SUM'
Treat the current values as integrated charge over the sampling interval and simply sum the values, after subtracting a baseline level.
None
Field is optional
Integration method for photodiode monitoring data. Deprecated: This config has been moved to cpExtractPtcTask, and will be removed after v26.
polynomialOrder¶
 Default
3
 Field type
 Range
[2,inf)
Degree of polynomial to fit. Must be at least 2.
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. Deprecated: This field is deprecated and will be removed after v26.
splineFitMaxIter¶
Maximum number of iterations for spline fit.
splineFitMaxRejectionPerIteration¶
Maximum number of rejections per iteration for spline fit.
splineFitMinIter¶
Minimum number of iterations for spline fit.
splineGroupingColumn¶
Column to use for grouping together points for Spline mode, to allow for different proportionality constants. If not set, no grouping will be done.
splineGroupingMinPoints¶
Minimum number of linearity points to allow grouping together points for Spline mode with splineGroupingColumn. This configuration is here to prevent misuse of the Spline code to avoid overfitting.
splineKnots¶
Number of spline knots to use in fit.
usePhotodiode¶
Use the photodiode info instead of the raw expTimes?