Index: /branches/pap_branch_080908/psModules/src/imcombine/pmSubtractionMatch.c
===================================================================
--- /branches/pap_branch_080908/psModules/src/imcombine/pmSubtractionMatch.c	(revision 19449)
+++ /branches/pap_branch_080908/psModules/src/imcombine/pmSubtractionMatch.c	(revision 19450)
@@ -98,5 +98,5 @@
 {
     if (region) {
-        varFactor *= (region->x1 - region->x1 + 1) * (region->y1 * region->y1 + 1) /
+        varFactor *= (region->x1 - region->x0 + 1) * (region->y1 - region->y0 + 1) /
             (ro->image->numCols * ro->image->numRows);
     }