Index: /trunk/src/org/openstreetmap/josm/data/imagery/GeorefImage.java
===================================================================
--- /trunk/src/org/openstreetmap/josm/data/imagery/GeorefImage.java	(revision 4013)
+++ /trunk/src/org/openstreetmap/josm/data/imagery/GeorefImage.java	(revision 4014)
@@ -95,5 +95,7 @@
         }
         default:
-            this.image = layer.sharpenImage(this.image);
+            if (this.image != null) {
+                this.image = layer.sharpenImage(this.image);
+            }
             break;
         }