Index: trunk/ippScripts/scripts/diff_skycell.pl
===================================================================
--- trunk/ippScripts/scripts/diff_skycell.pl	(revision 38071)
+++ trunk/ippScripts/scripts/diff_skycell.pl	(revision 38709)
@@ -78,6 +78,8 @@
 # XXX camera is not known here; cannot use filerules... 
 my $logDest = "$outroot.log";
+my $updateMode = 0;
 if ($run_state eq 'update') {
     $logDest .= '.update';
+    $updateMode = 1;
 }
 $ipprc->redirect_to_logfile($logDest) or my_die( "Unable to redirect output", $diff_id, $skycell_id, $PS_EXIT_SYS_ERROR ) if $redirect;
@@ -322,5 +324,6 @@
     }
 
-    # use WARPSTATS if we're updating, as we don't care about the new stuff from the STACK and DIFF STATS recipes
+    # use WARPSTATS if we're updating, as we don't care about the new stuff from the STACK and DIFF STATS recipes.
+    # The only value that we use is -quality
     $recipe_ppstats = 'WARPSTATS';
 }
@@ -351,4 +354,5 @@
 {
     my $command = "$ppSub $outroot";
+    $command .= " -updatemode" if $updateMode;
     $command .= " -inimage $input";
     $command .= " -refimage $template";