Index: trunk/psModules/src/imcombine/pmReadoutCombine.c
===================================================================
--- trunk/psModules/src/imcombine/pmReadoutCombine.c	(revision 24622)
+++ trunk/psModules/src/imcombine/pmReadoutCombine.c	(revision 24791)
@@ -173,4 +173,6 @@
     for (int i = 0; i < inputs->n; i++) {
         pmReadout *readout = inputs->data[i]; // Readout of interest
+	psAssert(readout, "readout was not defined");
+	if (!readout->process) continue;
         if (!readout->image) {
             psError(PS_ERR_UNEXPECTED_NULL, true, "Image data is missing for image %d.\n", i);
@@ -271,4 +273,5 @@
         for (int r = 0; r < inputs->n; r++) {
             pmReadout *readout = inputs->data[r]; // Input readout
+            if (!readout->process) continue; 
             psTrace("psModules.imcombine", 3, "Iterating input %d: %d --> %d, %d --> %d\n", r,
                     minInputCols - readout->col0, maxInputCols - readout->col0,
@@ -308,4 +311,8 @@
             for (int r = 0; r < inputs->n; r++) {
                 pmReadout *readout = inputs->data[r]; // Input readout
+		if (!readout->process) {
+		    maskData[r] = 1;
+		    continue;
+		}
                 int yIn = i - readout->row0; // y position on input readout
                 int xIn = j - readout->col0; // x position on input readout