BrighterFatterKernelSolveTask¶

BrighterFatterKernelSolveTask inverts the covariance matrix from a photon transfer curve dataset to produce a brighter-fatter kernel.

Processing summary¶

BrighterFatterKernelSolveTask runs these operations:

Scale and normalize the covariance matrix.
Tile the covariance matrix to produce the cross-correlation in all four quadrants.
Invert cross-correlation through successive over relaxation process.
Optionally average the per-amplifier kernels into a per-detector kernel.

Python API summary¶

from lsst.cp.pipe.cpBfk import BrighterFatterKernelSolveTask

classBrighterFatterKernelSolveTask(*, config=None, log=None, initInputs=None, **kwargs): Measure appropriate Brighter-Fatter Kernel from the PTC dataset...

attributeconfig: Access configuration fields and retargetable subtasks.

methodrun(inputPtc, dummy, camera, inputDims): Combine covariance information from PTC into brighter-fatter kernels...

Retargetable subtasks¶

No subtasks.

Configuration fields¶

connections¶

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

Configurations describing the connections of the PipelineTask to datatypes

correlationModelRadius¶

Default: 100
Field type: int Field

Build a model of the correlation coefficients for radii larger than this value in pixels?

correlationModelSlope¶

Default: -1.35
Field type: float Field

Slope of the correlation model for radii larger than correlationModelRadius

correlationQuadraticFit¶

Default: False
Field type: bool Field

Use a quadratic fit to find the correlations instead of simple averaging?

covModelFluxSample¶

Default: {'ALL_AMPS': 25000.0}
Field type: DictField
Key type: str
Value type: float

Flux level in electrons at which to sample the full covariancemodel if useCovModelSample=True. The same level is applied to allamps if this parameter [dict] is passed as {‘ALL_AMPS’: value}

eLevelSuccessiveOverRelaxation¶

Default: 5e-14
Field type: float Field

The target residual error for the successive over-relaxation method

forceZeroSum¶

Default: True
Field type: bool Field

Force the correlation matrix to have zero sum by adjusting the (0,0) value?Defaults to true bsed on recommendation of Broughton et al. 2024.

ignoreAmpsForAveraging¶

Default: []
Field type: str ListField

List of amp names to ignore when averaging the amplifier kernels into the detector kernel. Only relevant for level = DETECTOR

level¶

Default

'AMP'

Field type

str ChoiceField (optional)

Choices

'AMP': Every amplifier treated separately
'DETECTOR': One kernel per detector
None: Field is optional

The level at which to calculate the brighter-fatter kernels

maxIterSuccessiveOverRelaxation¶

Default: 10000
Field type: int Field

The maximum number of iterations allowed for the successive over-relaxation method

nSigmaClip¶

Default: 5
Field type: float Field

Number of sigma to clip when calculating means for the cross-correlation

saveLogOutput¶

Default: True
Field type: bool Field

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

useAmatrix¶

Default: False
Field type: bool Field

Use the PTC ‘a’ matrix (Astier et al. 2019 equation 20) instead of the average of measured covariances?

useCovModelSample¶

Default: False
Field type: bool Field

Use the covariance matrix sampled from the full covariance model (Astier et al. 2019 equation 20) instead of the average measured covariances?

xcorrCheckRejectLevel¶

Default: 2.0
Field type: float Field

Rejection level for the sum of the input cross-correlations. Arrays which sum to greater than this are discarded before the clipped mean is calculated.

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