Index: trunk/psModules/src/imcombine/pmSubtractionMatch.c
===================================================================
--- trunk/psModules/src/imcombine/pmSubtractionMatch.c	(revision 16403)
+++ trunk/psModules/src/imcombine/pmSubtractionMatch.c	(revision 16405)
@@ -311,10 +311,14 @@
                 psMetadataAddPtr(conv1->analysis, PS_LIST_TAIL, PM_SUBTRACTION_ANALYSIS_KERNEL,
                                  PS_DATA_UNKNOWN | PS_META_DUPLICATE_OK, "Subtraction kernels", kernels);
-                psMetadataAddPtr(conv2->analysis, PS_LIST_TAIL, PM_SUBTRACTION_ANALYSIS_KERNEL,
-                                 PS_DATA_UNKNOWN | PS_META_DUPLICATE_OK, "Subtraction kernels", kernels);
+                if (conv2) {
+                    psMetadataAddPtr(conv2->analysis, PS_LIST_TAIL, PM_SUBTRACTION_ANALYSIS_KERNEL,
+                                     PS_DATA_UNKNOWN | PS_META_DUPLICATE_OK, "Subtraction kernels", kernels);
+                }
                 psMetadataAddS32(conv1->analysis, PS_LIST_TAIL, PM_SUBTRACTION_ANALYSIS_MODE,
                                  PS_DATA_UNKNOWN | PS_META_DUPLICATE_OK, "Subtraction kernels", mode);
-                psMetadataAddS32(conv2->analysis, PS_LIST_TAIL, PM_SUBTRACTION_ANALYSIS_MODE,
-                                 PS_DATA_UNKNOWN | PS_META_DUPLICATE_OK, "Subtraction kernels", mode);
+                if (conv2) {
+                    psMetadataAddS32(conv2->analysis, PS_LIST_TAIL, PM_SUBTRACTION_ANALYSIS_MODE,
+                                     PS_DATA_UNKNOWN | PS_META_DUPLICATE_OK, "Subtraction kernels", mode);
+                }
                 psRegion *subRegion;
                 if (region) {
@@ -326,7 +330,9 @@
                                   PS_DATA_REGION | PS_META_DUPLICATE_OK,
                                  "Region over which subtraction was performed", subRegion);
-                psMetadataAddPtr(conv2->analysis, PS_LIST_TAIL, PM_SUBTRACTION_ANALYSIS_REGION,
-                                  PS_DATA_REGION | PS_META_DUPLICATE_OK,
-                                 "Region over which subtraction was performed", subRegion);
+                if (conv2) {
+                    psMetadataAddPtr(conv2->analysis, PS_LIST_TAIL, PM_SUBTRACTION_ANALYSIS_REGION,
+                                     PS_DATA_REGION | PS_META_DUPLICATE_OK,
+                                     "Region over which subtraction was performed", subRegion);
+                }
                 psFree(subRegion);
             }