DecorrelateALKernelSpatialTask¶
-
class
lsst.ip.diffim.
DecorrelateALKernelSpatialTask
(*args, **kwargs)¶ Bases:
lsst.pipe.base.Task
Decorrelate the effect of convolution by Alard-Lupton matching kernel in image difference
Notes
Pipe-task that removes the neighboring-pixel covariance in an image difference that are added when the template image is convolved with the Alard-Lupton PSF matching kernel.
This task is a simple wrapper around @ref DecorrelateALKernelTask, which takes a
spatiallyVarying
parameter in itsrun
method. If it isFalse
, then it simply calls therun
method of @ref DecorrelateALKernelTask. If it is True, then it uses the @ref ImageMapReduceTask framework to break the exposures into subExposures on a grid, and performs therun
method of @ref DecorrelateALKernelTask on each subExposure. This enables it to account for spatially-varying PSFs and noise in the exposures when performing the decorrelation.This task has no standalone example, however it is applied as a subtask of pipe.tasks.imageDifference.ImageDifferenceTask. There is also an example of its use in
tests/testImageDecorrelation.py
.Methods Summary
computeVarianceMean
(exposure)Compute the mean of the variance plane of exposure
.emptyMetadata
()Empty (clear) the metadata for this Task and all sub-Tasks. getAllSchemaCatalogs
()Get schema catalogs for all tasks in the hierarchy, combining the results into a single dict. getFullMetadata
()Get metadata for all tasks. getFullName
()Get the task name as a hierarchical name including parent task names. getName
()Get the name of the task. getSchemaCatalogs
()Get the schemas generated by this task. getTaskDict
()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
(scienceExposure, templateExposure, …)Perform decorrelation of an image difference exposure. timer
(name[, logLevel])Context manager to log performance data for an arbitrary block of code. Methods Documentation
-
computeVarianceMean
(exposure)¶ Compute the mean of the variance plane of
exposure
.
-
emptyMetadata
()¶ Empty (clear) the metadata for this Task and all sub-Tasks.
-
getAllSchemaCatalogs
()¶ Get schema catalogs for all tasks in the hierarchy, combining the results into a single dict.
Returns: - schemacatalogs :
dict
Keys are butler dataset type, values are a empty catalog (an instance of the appropriate
lsst.afw.table
Catalog type) for all tasks in the hierarchy, from the top-level task down through all subtasks.
Notes
This method may be called on any task in the hierarchy; it will return the same answer, regardless.
The default implementation should always suffice. If your subtask uses schemas the override
Task.getSchemaCatalogs
, not this method.- schemacatalogs :
-
getFullMetadata
()¶ 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.
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.- metadata :
-
getFullName
()¶ 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 :
-
getSchemaCatalogs
()¶ Get the schemas generated by this task.
Returns: - schemaCatalogs :
dict
Keys are butler dataset type, values are an empty catalog (an instance of the appropriate
lsst.afw.table
Catalog type) for this task.
See also
Task.getAllSchemaCatalogs
Notes
Warning
Subclasses that use schemas must override this method. The default implementation returns an empty dict.
This method may be called at any time after the Task is constructed, which means that all task schemas should be computed at construction time, not when data is actually processed. This reflects the philosophy that the schema should not depend on the data.
Returning catalogs rather than just schemas allows us to save e.g. slots for SourceCatalog as well.
- schemaCatalogs :
-
getTaskDict
()¶ 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)¶ Make a
lsst.pex.config.ConfigurableField
for this task.Parameters: - doc :
str
Help text for the field.
Returns: - configurableField :
lsst.pex.config.ConfigurableField
A
ConfigurableField
for this task.
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")
- doc :
-
makeSubtask
(name, **keyArgs)¶ 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”.
Notes
The subtask must be defined by
Task.config.name
, an instance ofConfigurableField
orRegistryField
.- name :
-
run
(scienceExposure, templateExposure, subtractedExposure, psfMatchingKernel, spatiallyVarying=True, preConvKernel=None, templateMatched=True, preConvMode=False)¶ Perform decorrelation of an image difference exposure.
Decorrelates the diffim due to the convolution of the templateExposure with the A&L psfMatchingKernel. If
spatiallyVarying
is True, it utilizes the spatially varying matching kernel via theimageMapReduce
framework to perform spatially-varying decorrelation on a grid of subExposures.Parameters: - scienceExposure :
lsst.afw.image.Exposure
the science Exposure used for PSF matching
- templateExposure :
lsst.afw.image.Exposure
the template Exposure used for PSF matching
- subtractedExposure :
lsst.afw.image.Exposure
the subtracted Exposure produced by
ip_diffim.ImagePsfMatchTask.subtractExposures()
- psfMatchingKernel : an (optionally spatially-varying) PSF matching kernel produced
by
ip_diffim.ImagePsfMatchTask.subtractExposures()
- spatiallyVarying :
bool
if True, perform the spatially-varying operation
- preConvKernel :
lsst.meas.algorithms.Psf
if not none, the scienceExposure has been pre-filtered with this kernel. (Currently this option is experimental.)
- templateMatched :
bool
, optional If True, the template exposure was matched (convolved) to the science exposure.
- preConvMode :
bool
, optional If True,
subtractedExposure
is assumed to be a likelihood difference image and will be noise corrected as a likelihood image.
Returns: - results :
lsst.pipe.base.Struct
a structure containing: -
correctedExposure
: the decorrelated diffim
- scienceExposure :
-
timer
(name, logLevel=10)¶ Context manager to log performance data for an arbitrary block of code.
Parameters: See also
timer.logInfo
Examples
Creating a timer context:
with self.timer("someCodeToTime"): pass # code to time
-