ComputeNoiseCorrelationTask¶
- class lsst.meas.algorithms.ComputeNoiseCorrelationTask(*args, **kwargs)¶
Bases:
Task
Compute the noise correlation coefficients in a MaskedImage
The variance plane in a convolved or warped image (or a coadd derived from warped images) does not accurately reflect the noise properties of the image because variance has been lost to covariance. This Task computes a matrix of correlation coefficients of a desired size. It assumes that the noise is (at least the correlation coefficients are) stationary and uses spatial averaging to compute the correlation coefficients.
Methods Summary
Empty (clear) the metadata for this Task and all sub-Tasks.
Get metadata for all tasks.
Get the task name as a hierarchical name including parent task names.
getName
()Get the name of the task.
Get a dictionary of all tasks as a shallow copy.
makeField
(doc)Make a
lsst.pex.config.ConfigurableField
for this task.makeSubtask
(name, **keyArgs)Create a subtask as a new instance as the
name
attribute of this task.run
(maskedImage[, refMaskedImage])Compute the correlation matrix from a maskedImage.
subtractedBackground
(maskedImage)Context manager for subtracting the background
timer
(name[, logLevel])Context manager to log performance data for an arbitrary block of code.
Methods Documentation
- getFullMetadata() TaskMetadata ¶
Get metadata for all tasks.
- Returns:
- metadata
TaskMetadata
The keys are the full task name. Values are metadata for the top-level task and all subtasks, sub-subtasks, etc.
- metadata
Notes
The returned metadata includes timing information (if
@timer.timeMethod
is used) and any metadata set by the task. The name of each item consists of the full task name with.
replaced by:
, followed by.
and the name of the item, e.g.:topLevelTaskName:subtaskName:subsubtaskName.itemName
using
:
in the full task name disambiguates the rare situation that a task has a subtask and a metadata item with the same name.
- getFullName() str ¶
Get the task name as a hierarchical name including parent task names.
- Returns:
- fullName
str
The full name consists of the name of the parent task and each subtask separated by periods. For example:
The full name of top-level task “top” is simply “top”.
The full name of subtask “sub” of top-level task “top” is “top.sub”.
The full name of subtask “sub2” of subtask “sub” of top-level task “top” is “top.sub.sub2”.
- fullName
- getName() str ¶
Get the name of the task.
- Returns:
- taskName
str
Name of the task.
- taskName
See also
getFullName
Get the full name of the task.
- getTaskDict() dict[str, weakref.ReferenceType[lsst.pipe.base.task.Task]] ¶
Get a dictionary of all tasks as a shallow copy.
- Returns:
- taskDict
dict
Dictionary containing full task name: task object for the top-level task and all subtasks, sub-subtasks, etc.
- taskDict
- classmethod makeField(doc: str) ConfigurableField ¶
Make a
lsst.pex.config.ConfigurableField
for this task.- Parameters:
- doc
str
Help text for the field.
- doc
- Returns:
- configurableField
lsst.pex.config.ConfigurableField
A
ConfigurableField
for this task.
- configurableField
Examples
Provides a convenient way to specify this task is a subtask of another task.
Here is an example of use:
class OtherTaskConfig(lsst.pex.config.Config): aSubtask = ATaskClass.makeField("brief description of task")
- makeSubtask(name: str, **keyArgs: Any) None ¶
Create a subtask as a new instance as the
name
attribute of this task.- Parameters:
- name
str
Brief name of the subtask.
- **keyArgs
Extra keyword arguments used to construct the task. The following arguments are automatically provided and cannot be overridden:
config
.parentTask
.
- name
Notes
The subtask must be defined by
Task.config.name
, an instance ofConfigurableField
orRegistryField
.
- run(maskedImage: MaskedImage, refMaskedImage: MaskedImage | None = None) CorrelationMatrix ¶
Compute the correlation matrix from a maskedImage.
- Parameters:
- maskedImage
MaskedImage
Image for which to determine the correlation matrix.
- refMaskedImage
MaskedImage
, optional Image from which to determine which pixels to mask. If None, it defaults to
maskedImage
.
- maskedImage
- Returns:
- corr_matrix
CorrelationMatrix
Correlation matrix of the maskedImage.
- corr_matrix
- Raises:
- RuntimeError
Raised if
refMaskedImage
is provided and does not have the same dimensions asmaskedImage
.
- subtractedBackground(maskedImage: MaskedImage)¶
Context manager for subtracting the background
We need to subtract the background so that the entire image (apart from objects, which should be clipped) will have the image/sqrt(variance) distributed about zero with unit variance. This context manager subtracts the background, and ensures it is restored on exit.
- Parameters:
- maskedImage
lsst.afw.image.MaskedImage
Image+mask+variance to have background subtracted and restored.
- maskedImage
- Returns:
- contextcontext manager
Context manager that ensure the background is restored.