# Question on HP 4p Scanjet Backend

John M. Mills (jmills@jmills.gtri.gatech.edu)
Thu, 3 Sep 1998 10:55:58 -0400 (EDT)

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First, thanks to all those who have provided SANE. As a relative newcomer
to scanning use, I have been very happy to use it. My setup is GNU/Linux
[;-) 2.0.35, still libc.so.5, low-end AHA1502e SCSI card, HP 4p Scanjet,
SANE 0.73 (about to go to 0.74), xscanimage, GIMP 0.99-31 (about to go to
1.0.0), and Canon BJC620 run through Ghostscript' 'uniprint' (and
reworking the printer's color map -- nearly there, I think). I am quite
happy with the usability and integration of these components, but not with
the results of scanning -- results are dark and short-scaled, it seems.

I notice in the HP backend notes a couple of unimplemented or non-working
features: downloadable tone maps and lineart in particular. Are these not
implemented because the information is not available to create them,
because the developers have moved on to other problems, or for some other
reason? If the information were available, I would like to hack at this a
bit: perhaps I could make some headway. My objective is that, if I can
download some color mapping information, the image will require less
color, brightness, and contrast manipulation when it has been scanned into
the 3@8-bit RGB model, and thus leave more range for fine adjustment in
GIMP without the shadow and highlight blocking I now see. In short, I
think that post-scan adjustments throw away dynamic range I cannot afford
to lose.

Would anyone who knows how to look into these limitations please suggest
where I should start? (I also have the option of working from Win95 and
the HP drivers, should there be a way to capture traffic in that
environment -- by writing a shim to the SCSI interface, for example.) I
realize I am quite ignorant and don't know what I'm biting off, but "...
even a blind pig finds an occasional acorn," as the local expression goes.

Thanks - mills

John M. Mills, Senior Research Engineer -- john.mills@gtri.gatech.edu
Georgia Tech Research Institute, Georgia Tech, Atlanta, GA 30332-0834
Phone contacts: 404.894.0151 (voice), 404.894.6285 (FAX)
"The cardinal virtues of a programmer are Laziness,
Impatience, and Hubris." -- attr. Larry Wall

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