fixed a problem about applying IPC effects twice when using the psf c…

…al path inside the gridded library

webbpsf/detectors.py

@@ -167,16 +167,21 @@ def apply_detector_ipc(psf_hdulist, extname = 'DET_DIST'):
 
     # In cases for which the user has asked for the IPC to be applied to a not-present extension, we have nothing to add this to
 
-    if psf_hdulist is  None: return
+    #if psf_hdulist is  None: return
     if extname not in psf_hdulist:
         webbpsf.webbpsf_core._log.debug(f"Skipping IPC simulation since ext {extname} is not found")
         return
 
+    # This avoid applying IPC corrections twice, especially when calling the psf_grid code path for making ePSFs
+    #  because the IPC corrections are applied in gridded_library
+
+    keyword = 'IPCINST'
+    if keyword in psf_hdulist[extname].header._keyword_indices: return
+
     inst = psf_hdulist[extname].header['INSTRUME'].upper()
     oversample = psf_hdulist[extname].header['OVERSAMP']
 
     kernel, meta = get_detector_ipc_model(inst, psf_hdulist[extname].header)
-
     if kernel is not None:
 
         if inst.upper()=='NIRCAM':

webbpsf/gridded_library.py

@@ -285,6 +285,13 @@ def create_grid(self):
                 if self.verbose is True:
                     print("    Position {}/{}: {} pixels".format(i+1, len(self.location_list), loc))
 
+                # Deactivate IPC corrections, if any, before calc_psf as we are applying them later
+                self.webb.options['add_ipc_gridded'] = False # add dictionary key to keep track of the user's IPC input
+                # Deactivate IPC corrections, if any, before calc_psf as we are applying them later
+                if self.webb.options.get('add_ipc', True):
+                    self.webb.options['add_ipc'] = False
+                    self.webb.options['add_ipc_gridded'] = True
+
                 # Create PSF
                 psf = self.webb.calc_psf(**self._kwargs)
                 if self.verbose is True:
@@ -296,7 +303,10 @@ def create_grid(self):
                 psf[ext].data = astropy.convolution.convolve(psf[ext].data, kernel)
 
                 # Convolve PSF with a model for interpixel capacitance
-                # This is apply outside the gridded libary see issue #736
+
+                if self.add_distortion and self.webb.options['add_ipc_gridded']:
+                    webbpsf.detectors.apply_detector_ipc(psf, extname=ext)
+                    self.webb.options['add_ipc'] = True # restore the dictionary keyword for the IPC
 
                 # Add PSF to 5D array
                 psf_arr[i, :, :] = psf[ext].data