Index: trunk/psphot/src/psphotSubtractBackground.c
===================================================================
--- trunk/psphot/src/psphotSubtractBackground.c	(revision 16820)
+++ trunk/psphot/src/psphotSubtractBackground.c	(revision 18836)
@@ -90,4 +90,5 @@
 
     // subtract the background model (save in backSub, if requested)
+    // XXX if needed, multithread this (fairly trivial)
     for (int j = 0; j < image->numRows; j++) {
         for (int i = 0; i < image->numCols; i++) {