Added mask planes from template and science fake plane into difference

python/lsst/ip/diffim/subtractImages.py

@@ -195,12 +195,12 @@ class AlardLuptonSubtractBaseConfig(lsst.pex.config.Config):
     )
     badMaskPlanes = lsst.pex.config.ListField(
         dtype=str,
-        default=("NO_DATA", "BAD", "SAT", "EDGE"),
+        default=("NO_DATA", "BAD", "SAT", "EDGE", "FAKE"),
         doc="Mask planes to exclude when selecting sources for PSF matching."
     )
     preserveTemplateMask = lsst.pex.config.ListField(
         dtype=str,
-        default=("NO_DATA", "BAD", "SAT"),
+        default=("NO_DATA", "BAD", "SAT", "FAKE"),
         doc="Mask planes from the template to propagate to the image difference."
     )
 
@@ -457,7 +457,8 @@ def runConvolveTemplate(self, template, science, selectSources):
                                      psfMatchingKernel=kernelResult.psfMatchingKernel)
 
     def runConvolveScience(self, template, science, selectSources):
-        """Convolve the science image with a PSF-matching kernel and subtract the template image.
+        """Convolve the science image with a PSF-matching kernel and subtract
+        the template image.
 
         Parameters
         ----------
@@ -560,6 +561,24 @@ def finalize(self, template, science, difference, kernel,
         mask = difference.mask
         mask &= ~(mask.getPlaneBitMask("DETECTED") | mask.getPlaneBitMask("DETECTED_NEGATIVE"))
 
+        # propagate the mask plane related to Fake source injection
+        # NOTE: the fake source injection sets FAKE plane, but it should be INJECTED
+        diffInjectedBitMask = mask.addMaskPlane("INJECTED")
+        diffInjectedTemplateBitMask = mask.addMaskPlane("INJECTED_TEMPLATE")
+
+        scienceFakeBit = science.mask.getPlaneBitMask('FAKE')
+        templateFakeBit = template.mask.getPlaneBitMask('FAKE')
+
+        deltaBitScience = diffInjectedBitMask - scienceFakeBit
+        deltaBitTemplate = diffInjectedTemplateBitMask - templateFakeBit
+
+        # get the arrays from the template and science that are flagged as FAKE
+        injectedScienceMaskArray = (science.mask.array & scienceFakeBit) * (2**deltaBitScience)
+        injectedTemplateMaskArray = (template.mask.array & templateFakeBit) * (2**deltaBitTemplate)
+
+        mask.array |= injectedScienceMaskArray
+        mask.array |= injectedTemplateMaskArray
+
         # We have cleared the template mask plane, so copy the mask plane of
         # the image difference so that we can calculate correct statistics
         # during decorrelation. Do this regardless of whether decorrelation is
@@ -570,7 +589,8 @@ def finalize(self, template, science, difference, kernel,
             # We have cleared the template mask plane, so copy the mask plane of
             # the image difference so that we can calculate correct statistics
             # during decorrelation
-            template[science.getBBox()].mask.array[...] = difference.mask.array[...]
+            # NOTE: following line is already being run outside the if statement.
+            # template[science.getBBox()].mask.array[...] = difference.mask.array[...]
             correctedExposure = self.decorrelate.run(science, template[science.getBBox()], difference, kernel,
                                                      templateMatched=templateMatched,
                                                      preConvMode=preConvMode,