I bought a HP Scanjet
G3110 a few months ago. The description of the SANE support for
this scanner is "basic" and that is accurate. I am using the
hp3900 driver as provided with OpenSuSE (sane-backends 1.0.25).
I can show you what I get. First, here is a photo I have taken
with my camera to establish a reference for comparison. http://freemans.id.au/images/photo-reduced.JPG
The white background depends on the level of illumination so it
will not allow a precise comparison with the scanned versions.