plustek: A3I scan quality issues
Subject:
Re: A3I scan quality issues
From:
Gene Heskett ####@####.####
Date:
24 Sep 2002 07:03:55 -0000
Message-Id: <200209240259.48212.gene_heskett@iolinc.net>
On Tuesday 24 September 2002 01:27, Derrick J Brashear wrote:
>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
This one looks somewhat like the first sample. The scnanners
resolution is less than the map though, and with the decimation to
get down to 200dpi, it does look out of focus.
>http://www.dementia.org/~shadow/out400.jpg
And this one still looks out of focus, but only the reds, and they
seem to be bleeding all ways around the compass here at 400. I
wonder if thats a jpg artifact now.
>
>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.
>
I hear that. The only reason I'm still half awake is I was running
memtest86 on a new stick of pc133 dimm. Its done, so its
bed-thirty at 3am here too.
--
Cheers, Gene
AMD K6-III@500mhz 320M
Athlon1600XP@1400mhz 512M
99.16% setiathome rank, not too shabby for a WV hillbilly
