Index: trunk/ppImage/src/ppImageReplaceBackground.c
===================================================================
--- trunk/ppImage/src/ppImageReplaceBackground.c	(revision 41382)
+++ trunk/ppImage/src/ppImageReplaceBackground.c	(revision 42382)
@@ -81,6 +81,14 @@
     if (!modelFile || !modelRO) {
         if (!psphotModelBackgroundReadoutFileIndex(config, &roView, "PPIMAGE.CHIP", 0)) {
-            psError(PS_ERR_UNKNOWN, false, "Unable to model background");
-            return false;
+            int lastError = psErrorCodeLast();
+	    if (lastError == PSPHOT_ERR_DATA) {
+	      // a data error in psphotModelBackground* means an empty or bad image: skip background subtraction
+	      psErrorStackPrint(stderr, "Unable to model background");
+	      psErrorClear();
+	      return true;
+	    } else {
+	      psError(PS_ERR_UNKNOWN, false, "Unable to model background");
+	      return false;
+	    }
         }
         // the model file should now at least be defined