plustek: A3I scan quality issues
Subject:
Re: A3I scan quality issues
From:
Derrick J Brashear ####@####.####
Date:
24 Sep 2002 05:32:23 -0000
Message-Id: <Pine.LNX.3.96L.1020924010153.17272C-100000@scully.trafford.dementia.org>
On Tue, 24 Sep 2002, Gene Heskett wrote:
> This looks as if the scanner is "out of focus", which to a scanner,
> (at least to my Epson 1250u) is equal to being out of registration.
>
> My problem with that statement is that since the scanner is a
> vertical motion device, the miss-registration is normally displayed
> in an up and down manner, not the left-right error we are seeing.
>
> Was this clip rotated 90 degrees maybe?
Nope.
> This looks to be a fairly low res scan, 300 dpi or so, what would it
150, maybe 200. Can't remember.
> look like at the scanners full resolution capability? This could
> be even more illuminating, if only to add to the puzzlement I have
> now. Since those maps are in all probability a half-tone process,
> we would need an image that exceeds the size of the halftone dots
> in working resolution, say 1200 or more dpi, more being better in
> this case. What I can see looks as if they about matched, and this
xscanimage only offers me up to 400dpi.
> is guaranteed to generate a moire pattern between the dots and the
> scanners working pixel size. That can get downright ugly results
> at times.
Well, note everything else at http://docs.unh.edu was scanned at 200dpi,
and there's no such problem. I know of what you speak, but these maps
don't appear to be printed that way.
> Registration, or focus is normally a function of the drivers
> compiled in data sources and would be adjustable with a re-compile
> after making the change in that variables value. Someone with
> intimate knowledge of that drivers setup would be needed unless the
> sources are well commented. The variable controls how close to the
> image plane the actual scanner tractor and its imager is as it
> travels down the page.
Hmm. I suspect then that I am sad.
On the other hand, from CHANGELOG:
Version 0.39 08/11/2001
...
6.0 Added A3I stuff aquired from Plustek
was this just the stuff which has since been commented out or was there
more? A search of the archives isn't turning up references to source, so
I'm guessing the source wasn't released generally, just the information.
(I have no gripe, I'm just wondering if that's the case)
I decided to try that (uncommenting the A3I stuff) and now I'm using that.
I can't tell for sure but I think it looks a bit better.
http://www.dementia.org/~shadow/out200.jpg
http://www.dementia.org/~shadow/out400.jpg
At 400 it looks reasonable. I think there's still a problem, but it's not
nearly as obvious. At 200 it still looks "weird".
I'm still reading source, but I may have to pick this up tomorrow.
