Index: trunk/ppMerge/src/ppMergeCombine.c
===================================================================
--- trunk/ppMerge/src/ppMergeCombine.c	(revision 11207)
+++ trunk/ppMerge/src/ppMergeCombine.c	(revision 12991)
@@ -191,9 +191,9 @@
 
                     if (options->shutter) {
-                        readout->image = pmShutterCorrectionMeasure(stack, options->shutterSize,
-                                                                    options->mean, options->stdev,
-                                                                    options->shutterIter,
-                                                                    options->shutterRej,
-                                                                    options->combine->maskVal);
+                        pmShutterCorrectionMeasure(readout, stack, options->shutterSize,
+                                                   options->mean, options->stdev,
+                                                   options->shutterIter,
+                                                   options->shutterRej,
+                                                   options->combine->maskVal);
                     } else {
                         pmReadoutCombine(readout, stack, cellZeros, cellScales, options->combine);