Index: trunk/ppSub/src/ppSubCamera.c
===================================================================
--- trunk/ppSub/src/ppSubCamera.c	(revision 18920)
+++ trunk/ppSub/src/ppSubCamera.c	(revision 19191)
@@ -119,4 +119,15 @@
     }
 
+    // Output subtraction kernel
+    pmFPAfile *outKernels = pmFPAfileDefineOutput(config, output->fpa, "PPSUB.OUTPUT.KERNELS");
+    if (!outKernels) {
+        psError(PS_ERR_IO, false, _("Unable to generate output file from PPSUB.OUTPUT.KERNELS"));
+        return false;
+    }
+    if (outKernels->type != PM_FPA_FILE_SUBKERNELS) {
+        psError(PS_ERR_IO, true, "PPSUB.OUTPUT.KERNELS is not of type SUBKERNELS");
+        return false;
+    }
+
 #if 0
     if (!pmFPAAddSourceFromFormat(output->fpa, "Subtraction", output->format)) {