diff --git a/backend/umax_pp.conf b/backend/umax_pp.conf
index 95b595a9a..54cfa59cd 100644
--- a/backend/umax_pp.conf
+++ b/backend/umax_pp.conf
@@ -8,30 +8,37 @@ option buffer 2097152
 
 # DEVICES #
 
-# specify the port your scanner is connected to. Possible are 0x378 (lp1)
-# 0x278 (lp2) and 0x3c8 (lp0)
+# specify the port your scanner is connected to. Possible are 0x378 (lp0)
+# 0x278 (lp2) and 0x3c8 (lp1)
+# on linux systems, you may provide the device name of the ppdev character device
+# /dev/parport0, /dev/parport1, ......
+# default is direct hardware access since ppdev is available for linux only
 port 0x378
 
 # the following options are local to this scanner
 # gain for red channel, if not given, will be automatically computed
 # must be between 0 and 15
-option red-gain 8
+#option red-gain 8
+
 # gain for red channel, if not given, will be automatically computed
 # must be between 0 and 15
-option green-gain 4
+#option green-gain 4
+
 # gain for red channel, if not given, will be automatically computed
 # must be between 0 and 15
-option blue-gain 8
+#option blue-gain 8
 
 # highlight for red channel, if not given, will default to 0
 # must be between 0 and 15
-option red-highlight 2
+#option red-highlight 2
+
 # highlight for red channel, if not given, will default to 0
 # must be between 0 and 15
-option green-highlight 1
+#option green-highlight 1
+
 # highlight for red channel, if not given, will default to 0
 # must be between 0 and 15
-option blue-highlight 1
+#option blue-highlight 1
 
 
 #
@@ -40,4 +47,8 @@ option blue-highlight 1
 #
 # valid values are 610, 1220, 1600 and 2000
 #
-option astra 1220
+# by default, no model, we rely on autodetection
+# in case you have black or 'inverted' scans, 
+# you may prevent detection by providing the
+# model number
+#option astra 1220