Comment 3 for bug 488070

Gelam, Thanks!!!!!

Just did the same for my Samsung SCX-4623F and now works perfectly. In my case it was:
echo "usb 0x04e8 0x3434" >> /etc/sane.d/xerox_mfp.conf

For everyone else with a Samsung multifunction/scanner, you can get the appropriate vendor ID and product ID with "sane-find-scanner":
$> sane-find-scanner
found USB scanner (vendor=0x04e8 [Samsung], product=0x3434 [SCX-4623 Series]) at libusb:001:010

In my case sane-find-scanner was always reporting the proper scanner found, but then it was not listed by scanimage -L. Also, scanimage -d xerox_mfp:libusb:001:010 was failing with "Invalid argument" (not after adding the line to xerox_mfp.conf)

After adding my scanner conf line to use the xerox_mfp backend as above, scanning works perfectly with the Simple Scanner in Lucid.