Index: trunk/psModules/src/imcombine/pmStackReject.c
===================================================================
--- trunk/psModules/src/imcombine/pmStackReject.c	(revision 30622)
+++ trunk/psModules/src/imcombine/pmStackReject.c	(revision 31203)
@@ -125,4 +125,10 @@
     PS_ASSERT_FLOAT_LARGER_THAN_OR_EQUAL(threshold, 0.0, NULL);
     PS_ASSERT_FLOAT_LESS_THAN_OR_EQUAL(threshold, 1.0, NULL);
+
+    if (!subRegions || !subKernels) {
+      psPixels *out = psPixelsCopy(NULL,in);
+      return out;
+    }
+    
     PS_ASSERT_ARRAY_NON_NULL(subRegions, NULL);
     PS_ASSERT_ARRAY_NON_NULL(subKernels, NULL);