Index: branches/pap/psModules/src/imcombine/pmSubtractionKernels.c
===================================================================
--- branches/pap/psModules/src/imcombine/pmSubtractionKernels.c	(revision 26300)
+++ branches/pap/psModules/src/imcombine/pmSubtractionKernels.c	(revision 26321)
@@ -111,14 +111,23 @@
 
 pmSubtractionKernels *p_pmSubtractionKernelsRawISIS(int size, int spatialOrder,
-                                                    const psVector *fwhms, const psVector *orders,
+                                                    const psVector *fwhmsIN, const psVector *ordersIN,
                                                     float penalty, pmSubtractionMode mode)
 {
-    PS_ASSERT_VECTOR_NON_NULL(fwhms, NULL);
-    PS_ASSERT_VECTOR_TYPE(fwhms, PS_TYPE_F32, NULL);
-    PS_ASSERT_VECTOR_NON_NULL(orders, NULL);
-    PS_ASSERT_VECTOR_TYPE(orders, PS_TYPE_S32, NULL);
-    PS_ASSERT_VECTORS_SIZE_EQUAL(fwhms, orders, NULL);
+    PS_ASSERT_VECTOR_NON_NULL(fwhmsIN, NULL);
+    PS_ASSERT_VECTOR_TYPE(fwhmsIN, PS_TYPE_F32, NULL);
+    PS_ASSERT_VECTOR_NON_NULL(ordersIN, NULL);
+    PS_ASSERT_VECTOR_TYPE(ordersIN, PS_TYPE_S32, NULL);
+    PS_ASSERT_VECTORS_SIZE_EQUAL(fwhmsIN, ordersIN, NULL);
     PS_ASSERT_INT_POSITIVE(size, NULL);
     PS_ASSERT_INT_NONNEGATIVE(spatialOrder, NULL);
+
+    // check the requested fwhm values: any values <= 0.0 should be dropped
+    psVector *fwhms  = psVectorAllocEmpty (fwhmsIN->n, PS_TYPE_F32);
+    psVector *orders = psVectorAllocEmpty (ordersIN->n, PS_TYPE_S32);
+    for (int i = 0; i < fwhmsIN->n; i++) {
+	if (fwhmsIN->data.F32[i] <= FLT_EPSILON) continue;
+	psVectorAppend(fwhms, fwhmsIN->data.F32[i]);
+	psVectorAppend(orders, ordersIN->data.S32[i]);
+    }
 
     int numGaussians = fwhms->n;       // Number of Gaussians