straylight.py

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# This file is part of ip_isr.
#
# Developed for the LSST Data Management System.
# This product includes software developed by the LSST Project
# (https://www.lsst.org).
# See the COPYRIGHT file at the top-level directory of this distribution
# for details of code ownership.
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
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from abc import abstractmethod
from typing import Optional
 
from lsst.pex.config import Config, Field, ListField
from lsst.pipe.base import Task
from lsst.geom import Angle
from .isrFunctions import checkFilter
from .calibType import IsrCalib
 
 
class StrayLightConfig(Config):
    doRotatorAngleCorrection = Field(
        dtype=bool,
        doc="",
        default=False,
    )
    # TODO DM-28093: change the doc to specify that these are physical labels
    filters = ListField(
        dtype=str,
        doc="Filters that need straylight correction.",
        default=[],
    )
 
 
class StrayLightTask(Task):
    """Remove stray light from instruments.
 
    This is a dummy task to be retargeted with an camera-specific version.
    """
    ConfigClass = StrayLightConfig
    _DefaultName = "isrStrayLight"
 
    def readIsrData(self, dataRef, rawExposure):
        """Read and return calibration products relevant for correcting
        stray light in the given exposure.
 
        Parameters
        ----------
        dataRef : `daf.persistence.butlerSubset.ButlerDataRef`
            Butler reference of the detector data to be processed
        rawExposure : `afw.image.Exposure`
            The raw exposure that will later be corrected with the
            retrieved calibration data; should not be modified in this
            method.
 
        Returns
        -------
        straylightData : `object`, optional
            An opaque object that should be passed as the second argument to
            the `run` method.  If `None`, no stray light correction will be
            performed for the given image.  Any other object (e.g. `True`)
            may be used to signal that stray light correction should be
            performed even if there is nothing to read.
 
        Notes
        -----
        This method will be called only when `IsrTask` is run by the Gen2
        Middleware (i.e. CmdLineTask).
        """
        return None
 
    def check(self, exposure):
        """Check if stray light correction should be run.
 
        Parameters
        ----------
        exposure : `lsst.afw.image.Exposure`
            Exposure to correct.
        """
        return False
 
    def run(self, exposure, strayLightData):
        """Correct stray light.
 
        Parameters
        ----------
        exposure : `lsst.afw.image.Exposure`
           Exposure to correct.
        strayLightData : `object`, optional
            An opaque object that contains any calibration data used to
            correct for stray light.
        """
        raise NotImplementedError("Must be implemented by subclasses.")
 
    def checkFilter(self, exposure):
        """Check whether we should fringe-subtract the science exposure.
 
        Parameters
        ----------
        exposure : `lsst.afw.image.Exposure`
            Exposure to check the filter of.
 
        Returns
        -------
        needsFringe : `bool`
            If True, then the exposure has a filter listed in the
            configuration, and should have the fringe applied.
        """
        return checkFilter(exposure, self.config.filters, log=self.log)
 
 
class StrayLightData(IsrCalib):
    """An abstract base class for rotator-dependent stray light information.
    """
 
    @abstractmethod
    def evaluate(self, angle_start: Angle, angle_end: Optional[Angle] = None):
        """Get a stray light array for a range of rotator angles.
 
        Parameters
        ----------
        angle_begin : `float`
            Instrument rotation angle at the start of the exposure.
        angle_end : `float`, optional
            Instrument rotation angle at the end of the exposure.
            If not provided, the returned array will reflect a snapshot at
            `angle_start`.
 
        Returns
        -------
        array : `numpy.ndarray`
            A stray-light background image for this exposure.
        """
        raise NotImplementedError("Must be implemented by subclasses.")