Access scanner from LTSP server and thin clients

There seem to be a permission issue with accessing usb scanners from LTSP server and connected thin clients. Logging in as normal users, you cannot access the connected scanner.

Running the scanimage command as a normal user 
ltsp@ltsp-ProLiant-DL380-G4:~$ scanimage -L
device `hp3900:libusb:001:011' is a Unknown RTS8822 chipset based flatbed scanner

while logging in as the root user, running the scanimage command gives the parameter of the connected scanner.
root@ltsp-ProLiant-DL380-G4:~# scanimage -L
device `hp3900:libusb:001:011' is a Hewlett-Packard Scanjet 3800 flatbed scanner

You can however use any scan utility, but you will need root access to do this. To correct this - Looking at the permission for the usb character file
ltsp@ltsp-ProLiant-DL380-G4:~$ lsusb
Bus 005 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 004 Device 005: ID 1c4f:0002 SiGma Micro
Bus 004 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 003 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 002 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 001 Device 011: ID 03f0:2605 Hewlett-Packard ScanJet 3800c
Bus 001 Device 009: ID 03f0:5c17 Hewlett-Packard
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub

The user/group permission to the usb character device responsible for the connected usb device has read & write for the root user and group.
ltsp@ltsp-ProLiant-DL380-G4:~$ ls -l /dev/bus/usb/001

total 0
crw-rw-r--  1 root root 189,  0 2011-10-11 00:28 001
crw-rw-r--+ 1 root lp   189,  8 2011-10-11 13:03 009
crw-rw-r--+ 1 root root 189, 10 2011-10-11 09:17 011

Change the group from root to users. (In my case, the group users has all ltsp client users in that group)
root@ltsp-ProLiant-DL380-G4:/dev/bus/usb/001# chgrp users 011
root@ltsp-ProLiant-DL380-G4:/dev/bus/usb/001# ls -al
total 0
drwxr-xr-x  2 root root      100 2011-10-11 09:10 .
drwxr-xr-x  7 root root      140 2011-10-11 00:28 ..
crw-rw-r--  1 root root  189,  0 2011-10-11 00:28 001
crw-rw-r--+ 1 root lp    189,  8 2011-10-11 13:03 009
crw-rw-r--+ 1 root users 189, 10 2011-10-11 09:17 011

And now.......
ltsp@ltsp-ProLiant-DL380-G4:~$ scanimage -L
device `hp3900:libusb:001:011' is a Hewlett-Packard Scanjet 3800 flatbed scanner
ltsp@ltsp-ProLiant-DL380-G4:~$