Subject:
Re: Antwort: Re: USB Test-Version 41_4
From:
Gene Heskett ####@####.####
Date:
10 Feb 2002 04:02:08 -0000
Message-Id: <20020210035757324.AAA628@mail.iolinc.net@there>
On Saturday 09 February 2002 11:56 am, Gene Heskett wrote:
>On Friday 08 February 2002 01:06 pm, Jaeger, Gerhard wrote:
>>Hi,
>>
>>in the meantime, I also got updated infos from Stefan Nilsen,
>>who has a HP2200c, this scanner now also works much better...
>>
>>I plan to release the next stuff during the weekend, with
>> support for warmup time and adjustmentof the scan-position via
>> the configuration file.
>>
>>Maybe I also manage to make custom gamma tables work...
>>
>>Guys, keep on testing and thanks for that...
>>We maybe also get the motor for the 1200dpi work
>> Gerhard
>>
>>> My shading problem is back too. And I think that may be
>>> reduced by more lamp warmup time before doing the calibration
>>> phase.
>
>On further testing, I just compared, in gimp, a 100dpi scan made
>with only the existing delays (not much) in the code 41_4, and
>one with an extra 60 seconds of sleep immediately after the call
>that turns it back on in plustek-usbio.c.
>
>No difference can be detected in side by side comparisons. I am
>getting the impression that either the lamp isn't such high
>quality, or the calibration strip in mine is caca. Those who
> got the first image I sent will note its moreso on the left
> than the right. And I'm approaching the end of the 90 day
> warranty period.
>
>Of interest might be that the first preview of the day doesn't
>show this effect quite as prominently as its a bit bleached
>compared to subsequent scans. But by re-running xsane and
>quitting to shut off the lamp, or unplugging the psu, and
> letting it rest for half an hour doesn't seem to do the same as
> an overnight offtime in this regard.
>
>Any other ideas on this? Or should I be boxing this one up for
> a trip back to Staples?
Yeah, I know, its poor form to answer ones own posts. I did take
it back and got another, same model. I've been playing with it
for a few hours now and can say that these cheaper ones don't
seem to be very consistent.
1. All the OriginY settings shifted by at least 20 units. The
scanner actually tracks such as to make a slight parallelogram,
quarter of a millimeter I'd guess, of interest only to architects
probably.
2. The shading problem still exists, but is now of a different
form (magenta on the left inch, yellow on the right inch) so I'm
somewhat convinced its the variability of the paint job on the
calibration strip. Experimentally, I moved the ShadingOriginY
down to about 140 which puts the calibration position actually on
the end of the paper being scanned. This stopped the shading, or
so I thought, but the paper wasn't as bright with two glass
surfaces to read it thru, so everything got shifted white and
probably bleached out the white inbalance.
Too bad they didn't extend the glass to the rear of the unit so
it was in the calibration light path too.
I figure there is a range multiplier someplace in the calibration
routines, one that can scale the whole thing to effectively
cancel the glass losses and restore the grey scale to the prior
range. If anyone can tell me which variable that may be, and in
what routine in backend/plustek-usbshading.c, I'd appreciate it.
3. On this one, I had to extend the 3508 in the top line of the
cap file to 3588 to get it to go just barely past an A4 page end.
I don't recall, and wasn't using the same sample to scan before I
got this one, but I don't think the previous one would go more
than a pixel or 5 past the end of a letter (11") page, so that
particular variable setting will need expanded a bit for A4 paper
users. From the looks of the drive and carriage at the
turnaround point, it might be able to go another 50 or so pixels
before hitting anything.
4. At 150 and 300 dpi, the stepper is fairly noisy, and in fact
managed to get stuck in place quite a few times, usually at the
active scan start position, but once or twice in the home
position, requireing I call kpm to kill the process, do a
powerdown on the scanner and restart the scan. This is maybe an
indication of the wrong phasing to the motor at those settings?
At 600 dpi, it was very quiet, and seemingly dead reliable. But
100+ meg files take forever to display... I sure wish I had my
scope on the motor for some definitive readings, but I've not yet
figured out a clean way to get into one of these things. :-)
5. What perms do I have to give this stuff so I can run it
non-root? I'm sick of looking at the warning signs...
--
Cheers, Gene
AMD K6-III@500mhz 320M
Athlon1600XP@1400mhz 512M
98.5+% setiathome rank, not too shabby for a hillbilly
