DM-19393: Delegate to StrayLightTask subclasses to load their data.

python/lsst/ip/isr/isrTask.py

@@ -865,6 +865,10 @@ def readIsrData(self, dataRef, rawExposure):
             - ``atmosphereTransmission`` : `lsst.afw.image.TransmissionCurve`
                 A ``TransmissionCurve`` that represents the throughput of the
                 atmosphere, assumed to be spatially constant.
+            - ``strayLightData`` : `object`
+                An opaque object containing calibration information for
+                stray-light correction.  If `None`, no correction will be
+                performed.
 
         Raises
         ------
@@ -928,6 +932,11 @@ def readIsrData(self, dataRef, rawExposure):
             sensorTransmission = None
             atmosphereTransmission = None
 
+        if self.config.doStrayLight:
+            strayLightData = self.strayLight.readIsrData(dataRef, rawExposure)
+        else:
+            strayLightData = None
+
         # Struct should include only kwargs to run()
         return pipeBase.Struct(bias=biasExposure,
                                linearizer=linearizer,
@@ -941,14 +950,15 @@ def readIsrData(self, dataRef, rawExposure):
                                filterTransmission=filterTransmission,
                                sensorTransmission=sensorTransmission,
                                atmosphereTransmission=atmosphereTransmission,
+                               strayLightData=strayLightData
                                )
 
     @pipeBase.timeMethod
     def run(self, ccdExposure, camera=None, bias=None, linearizer=None, crosstalkSources=None,
             dark=None, flat=None, bfKernel=None, defects=None, fringes=None,
             opticsTransmission=None, filterTransmission=None,
             sensorTransmission=None, atmosphereTransmission=None,
-            detectorNum=None, isGen3=False
+            detectorNum=None, strayLightData=None, isGen3=False,
             ):
         """!Perform instrument signature removal on an exposure.
 
@@ -1013,6 +1023,9 @@ def run(self, ccdExposure, camera=None, bias=None, linearizer=None, crosstalkSou
             The integer number for the detector to process.
         isGen3 : bool, optional
             Flag this call to run() as using the Gen3 butler environment.
+        strayLightData : `object`, optional
+            Opaque object containing calibration information for stray-light
+            correction.  If `None`, no correction will be performed.
 
         Returns
         -------
@@ -1234,9 +1247,12 @@ def run(self, ccdExposure, camera=None, bias=None, linearizer=None, crosstalkSou
             self.debugView(ccdExposure, "doFringe")
 
         if self.config.doStrayLight:
-            self.log.info("Applying stray light correction.")
-            self.strayLight.run(ccdExposure)
-            self.debugView(ccdExposure, "doStrayLight")
+            if strayLightData is not None:
+                self.log.info("Applying stray light correction.")
+                self.strayLight.run(ccdExposure, strayLightData)
+                self.debugView(ccdExposure, "doStrayLight")
+            else:
+                self.log.debug("Skipping stray light correction: no data found for this image.")
 
         if self.config.doFlat:
             self.log.info("Applying flat correction.")

python/lsst/ip/isr/straylight.py

@@ -39,14 +39,44 @@ class StrayLightTask(Task):
     """
     ConfigClass = StrayLightConfig
 
-    def run(self, exposure, **kwargs):
+    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 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.
         """
-        self.log.info("The generic StrayLightTask does not correct anything.")
-        return
+        raise NotImplementedError("Must be implemented by subclasses.")