Index: branches/pap/psModules/src/imcombine/pmSubtractionEquation.c
===================================================================
--- branches/pap/psModules/src/imcombine/pmSubtractionEquation.c	(revision 25899)
+++ branches/pap/psModules/src/imcombine/pmSubtractionEquation.c	(revision 26007)
@@ -228,7 +228,8 @@
                     double ab = iConv1->kernel[y][x] * jConv2->kernel[y][x];
 #ifdef USE_VARIANCE
-                    aa /= variance->kernel[y][x];
-                    bb /= variance->kernel[y][x];
-                    ab /= variance->kernel[y][x];
+                    float var = 1.0 / variance->kernel[y][x];
+                    aa /= var;
+                    bb /= var;
+                    ab /= var;
 #endif
                     sumAA += aa;