Index: /trunk/ppMerge/src/ppMergeScaleZero.c
===================================================================
--- /trunk/ppMerge/src/ppMergeScaleZero.c	(revision 26653)
+++ /trunk/ppMerge/src/ppMergeScaleZero.c	(revision 26654)
@@ -114,8 +114,10 @@
                                         "--- setting to unity.",
                                         view->chip, view->cell, view->readout, i);
-                              psMetadataItem *item = psMetadataLookup(cell->concepts,
-                                                                      "CELL.GAIN"); // Item with gain
+                              psMetadataItem *item = psMetadataLookup(cell->concepts, "CELL.GAIN"); // Item with gain
                               psAssert(item, "Should be there!");
                               item->data.F32 = 1.0;
+			      
+			      // for unity gain, there is no modification for the readnoise, note that it has (effectively) been updated
+			      psMetadataRemoveKey(cell->concepts, "CELL.READNOISE.UPDATE");
                           } else {
                               // psError(PS_ERR_BAD_PARAMETER_VALUE, false,