Index: trunk/psModules/src/imcombine/pmSubtractionKernels.c
===================================================================
--- trunk/psModules/src/imcombine/pmSubtractionKernels.c	(revision 14538)
+++ trunk/psModules/src/imcombine/pmSubtractionKernels.c	(revision 14539)
@@ -597,6 +597,7 @@
                     }
                     // Normalise kernel component to unit sum
-                    psBinaryOp(poly, poly, "*", psScalarAlloc(1.0 / norm, PS_TYPE_F32));
-
+                    if (uOrder % 2 == 0 && vOrder % 2 == 0) {
+                        psBinaryOp(poly, poly, "*", psScalarAlloc(1.0 / norm, PS_TYPE_F32));
+                    }
                 }