Index: trunk/psModules/src/imcombine/pmSubtractionAnalysis.c
===================================================================
--- trunk/psModules/src/imcombine/pmSubtractionAnalysis.c	(revision 20051)
+++ trunk/psModules/src/imcombine/pmSubtractionAnalysis.c	(revision 20052)
@@ -174,13 +174,14 @@
         double m00 = 0, m10 = 0, m01 = 0, m20 = 0, m11 = 0, m02 = 0; // Moments to calculate
         int size = kernels->size;       // Half-size of kernel
-        for (int y = -size; y <= size; y++) {
-            for (int x = -size; x <= size; x++) {
+        int fullSize = 2 * size + 1;    // Full size of kernel
+        for (int y = 0, v = -size; y < fullSize; y++, v++) {
+            for (int x = 0, u = -size; x < fullSize; x++, u++) {
                 float value = image->data.F32[y][x]; // Value of kernel
                 m00 += value;
-                m10 += x * value;
-                m01 += y * value;
-                m20 += x * x * value;
-                m11 += x * y * value;
-                m02 += y * y * value;
+                m10 += u * value;
+                m01 += v * value;
+                m20 += u * u * value;
+                m11 += u * v * value;
+                m02 += v * v * value;
             }
         }