Index: /trunk/Mars/mimage/MImgCleanTime.cc
===================================================================
--- /trunk/Mars/mimage/MImgCleanTime.cc	(revision 18285)
+++ /trunk/Mars/mimage/MImgCleanTime.cc	(revision 18286)
@@ -99,4 +99,7 @@
     const Float_t time1 = pix1.GetArrivalTime();
 
+    if (pix1.IsPixelUnmapped())
+        return Island(0,time1);
+
     Island island(pix1.GetNumPhotons(), time1);
 
@@ -106,4 +109,6 @@
 
         MSignalPix &pix2 = (*fEvt)[idx2];
+        if (pix2.IsPixelUnmapped())
+            continue;
 
         const Int_t island2 = pix2.GetIdxIsland();
@@ -137,10 +142,11 @@
 Int_t MImgCleanTime::Process()
 {
-    // The assumption is that all pixels contain valid data
+    // The assumption is that all mapped pixels contain valid data
     const UInt_t npix = fEvt->GetNumPixels();
     for (UInt_t i=0; i<npix; i++)
     {
         MSignalPix &pix = (*fEvt)[i];
-        pix.SetPixelUnused();
+        if (!pix.IsPixelUnmapped())
+            pix.SetPixelUnused();
         pix.SetPixelCore(kFALSE);
         pix.SetIdxIsland(-1);
@@ -182,5 +188,5 @@
         // The ideal cut would be to allow that a single
         // pixel still can connect two clusters
-        if (I1.count==1 || I1.count==1)
+        if (I1.count==1 || I2.count==1)
             continue;