diff --git a/ETA.py b/ETA.py
index 71be064..de06ba3 100644
--- a/ETA.py
+++ b/ETA.py
@@ -605,24 +605,27 @@ fall = np.array( [
     ) for consecutive in fall if len( consecutive ) > 20 # the value might change
 ] ).astype( int )
 
-stairs = np.zeros( ( size_y , size_x ) )
+stairs = np.zeros( ( len( fall ) - 1 , size_x ) )
 for x in range( size_x ):
     stairs[ : fall[0] , x ] = 0 # TODO: put the mean
     for i in range( len( fall ) - 1 ):
-        stairs[ fall[ i ] : fall[ i + 1 ] , x ] = np.mean( data[
+        stairs[ i , x ] = np.mean( data[
             calibrations[ 'top' ][ 'y' ][ 'max' ] + fall[ i ] : calibrations[ 'top' ][ 'y' ][ 'max' ] + fall[ i + 1 ],
             border[ 'x' ][ 'min' ] + x
         ] )
-    stairs[ fall[ -1 ] : , x ] = 0
 
 if verbose:
     print( 'ETA flattened' )
     print( 'outputting data' )
 
 if output == None:
-    print( stairs )
+    print( stairs , wavelength )
 else:
-    np.savetxt( output , stairs )
+
+    output_file = pathlib.Path( output )
+    with shelve.open( str( output_file ) ) as output:
+        output[ 'data'   ]     = data
+        output[ 'wavelength' ] = wavelength
 
 if verbose:
     print( 'output sent' )