Index: branches/pap/psModules/src/imcombine/pmSubtractionKernels.c
===================================================================
--- branches/pap/psModules/src/imcombine/pmSubtractionKernels.c	(revision 23948)
+++ branches/pap/psModules/src/imcombine/pmSubtractionKernels.c	(revision 25027)
@@ -145,10 +145,8 @@
 
                 // Calculate moments
-                double sum = 0.0;       // Sum of kernel component, for normalisation
                 double moment = 0.0;    // Moment, for penalty
                 for (int v = -size, y = 0; v <= size; v++, y++) {
                     for (int u = -size, x = 0; u <= size; u++, x++) {
                         double value = xKernel->data.F32[x] * yKernel->data.F32[y]; // Value of kernel
-                        sum += value;
                         moment += value * (PS_SQR(u) + PS_SQR(v));
                     }
@@ -163,8 +161,8 @@
                         }
                     }
-                    sum = 1.0 / sum;
+                    sum = 1.0 / sqrt(sum);
                     psBinaryOp(xKernel, xKernel, "*", psScalarAlloc(sum, PS_TYPE_F32));
                     psBinaryOp(yKernel, yKernel, "*", psScalarAlloc(sum, PS_TYPE_F32));
-                    moment *= sum;
+                    moment *= PS_SQR(sum);
                 }