plustek: Thread: A3I scan quality issues

I'm not sure I have the expertise to do anything useful, but I'm willing
to try working at it. Anyone have hints as to what the problem might be?

I got the A3I so I can scan maps in halves instead of quarters (see
http://docs.unh.edu for some of the coverage; The stuff I'm scanning will
be online elsewhere soon and I can send a URL for raw scans without the
HTML "extras" if anyone cares.) but until I rectify the scan quality
issues I either need to use Windows or use the older scanner and scan in
quarters.

On Mon, 23 Sep 2002, Derrick J Brashear wrote:

> I'm not sure I have the expertise to do anything useful, but I'm willing
> to try working at it. Anyone have hints as to what the problem might be?

http://www.dementia.org/~shadow/out.jpg

it was blown up by xv to illustrate the point

the solid red background is true; the rainbow effect on the map scale is
presumably pointing at some color channel error, an offset, because the
scale is solid black, not color at all. 

I'm reading source now, but if anyone has a hint as to where to start,
that would be helpful.

Right now I'm looking through p48xx.c

-D

On Tuesday 24 September 2002 00:26, Derrick J Brashear wrote:
>On Mon, 23 Sep 2002, Derrick J Brashear wrote:
>> I'm not sure I have the expertise to do anything useful, but I'm
>> willing to try working at it. Anyone have hints as to what the
>> problem might be?
>
>http://www.dementia.org/~shadow/out.jpg
>
>it was blown up by xv to illustrate the point
>
>the solid red background is true; the rainbow effect on the map
> scale is presumably pointing at some color channel error, an
> offset, because the scale is solid black, not color at all.
>
>I'm reading source now, but if anyone has a hint as to where to
> start, that would be helpful.
>
>Right now I'm looking through p48xx.c
>
>-D

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?

This looks to be a fairly low res scan, 300 dpi or so, what would it 
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 
is guaranteed to generate a moire pattern between the dots and the 
scanners working pixel size.  That  can get downright ugly results 
at times.

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.

-- 
Cheers, Gene
AMD K6-III@500mhz 320M
Athlon1600XP@1400mhz  512M
99.16% setiathome rank, not too shabby for a WV hillbilly

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.

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

Hi Derrick,

to be honest, the A3I problem hasn't still solved so far, as there
seemed to be nobody outside, who was really interested in using this one.
I have one test device at home and also the original driver codes from
Plustek. Some of the stuff has found its way into the distribution, some
not because the code made the other devices stop working so far.

I remember, that I made the scanner work once, but I could not
find the code anymore, so I have to do all the work again...

We might can discuss the problem in private if you're really
interested in make the scanner work with linux...

Gerhard