Subject:
Re: epson 1250 perfection usb scanner
From:
Gene Heskett ####@####.####
Date:
1 Jun 2002 13:50:16 -0000
Message-Id: <200206010938.01808.gene_heskett@iolinc.net>
On Saturday 01 June 2002 06:30 am, Jaeger, Gerhard wrote:
>Hi Tom,
>
>this picture reminds me of some earlier tries with the driver...
>I thought - Gene correct me - that the color problems are gone so
> far. The only thing that is still missing is some sort of
> dark-calibration but the colors should not be that bad...
>Can please try the latest 1.0.8 SANE stuff?
>
>Gerhard
Its useable here with the last 1.07-tar.gz build, Gerhard. Not
perfect, but useable, main complaint is a yellow to magenta
highlight shift along the edges, but the white clipping in actually
putting it back on paper with gimp-print from gimp usually reduces
that to near vanishing. And one other effect I've noted several
times but which seems rather ephemeral is that if it sits idle for
a day or more, the first scan is absolutely beautifull, but the
next and all subsequent scans, even if shut down during the workday
for several hours, show this high-light shading that makes it look
as if the lamp isn't warmed up and uniform. I have mine set for a
near one minute warmup as you can see below.
If one looks really close to a scan of a chemical photograph, a
multicolored vertical pattern of pixels can be seen in the grey
areas below that brightness that would represent about half the
brightness of a kodak 18% grey card, and going on down to black
from there.
At risk of making it set stakes and call a surveyer slow, it would
be nice if a black sample were taken (in color at the same
resolution currently in use) and that were then subtracted from
each line of data that came in, which should subtract a large
amount of that. That wouldn't be too slow, but the next step is to
save the white sample, derive a difference from the ideal gain on a
pixel by pixel basis for all 3 colors, and then multiply each color
pixel in each line received by this 'per pixel' gain coefficient
for this pixel in the white balance sample. That would slow it
down some even if the cpu's math unit doesn't have the infamous
pentium bug. I of course have NDI how to go about that!
OTOH, we are trying to make a 100 dollar scanner look like a 2000
dollar scanner here, which may not be possible in the grand scheme
of things due to entropy of the universe or some such limiting
effect. :-)
>On Thursday, 30. May 2002 17:05, Tom Hull wrote:
>> I have the Epson 1250 Perfection USB scanner "working" -- i.e.,
>> the scanner runs and sends data which I can see sort of
>> resembles the image I'm scanning. However, the results strike me
>> as much more than a "calibration" problem. Please take a look
>> at:
>>
>> http://www.tomhull.com/scan1.jpg
>>
>> This is a 40k jpeg reduction of the scan of a book cover which
>> is mostly black text on white background. As you can see,
>> overall there is a lot of red, and there is a lot of banding.
>> When I fiddle with the xsane brightness controls, it looks to me
>> like the red channel is coherent but oversaturated; the blue and
>> green channels, OTOH, show the banding but no coherent image.
>>
>> My plustek.conf file matches the one posted by Gene Heskett,
>> including:
>>
>> option lampOff 600
>> option warmup 180
>> option lOffOnEnd 1
>>
>> However, once the lamp comes on it stays on indefinitely. (Turns
>> off when rebooting.)
That sounds like he has a very early 1.07 cvs version. Mine does
indeed shut down when I quit the program xsane. And at one point,
it was returning a patterned but non-sensical raster of data.
>> "Jaeger, Gerhard" wrote:
>> > Hi Tom,
>> >
>> > On Freitag, 24. Mai 2002 06:34, Tom Hull wrote:
>> > [SNIP]
>> >
>> > > Also, is there any reason not to think that it will
>> > > eventually work pretty well? (While I can still afford to
>> > > take it back.)
>> >
>> > Well, the main problem currently is the calibration. But do a
>> > test on your own before bringing it back...
--
Cheers, Gene
AMD K6-III@500mhz 320M
Athlon1600XP@1400mhz 512M
98.96+% setiathome rank, not too shabby for a hillbilly
