# Re: Calibration problem on UMAX Astra 1220S

Dean Martin Townsley (townsley@physics.ucsb.edu)
Thu, 25 Mar 1999 21:43:05 -0800

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> > > My problem with the calibration is simple: I can't get it to perform the
> > > calibration. I'm using sane 1.00 with the build-1 patch for the umax drivers
>
[snip]
> this appears abnormal, even for stuff on white backgrounds. I am under the
> ipression that this is what the "Quality Calibration" is for (though I could
> be wrong) is to set the white point so that it is not out of the scanner's
> sensing range, as it apparently is on mine since white and off-white come up
> as the same color -- ffffff white. I would assume it's just an impossible

Ok, well after some time perusing the source and looking at the UMAX docs I
find I have convinced myself that "Quality Calibration" is not necessarily
for adjustment of white point. There is other calibration stuff, such as
that done by the driver, and the kind with the different modes. But from
looking at the docs this option sets the quality bit in the scan command
block which chooses between "do quality calibration" and "do speed
calibration".
From my trials setting or not setting this bit seems to have very little
effect on the scan. So this leads to two questions: What does the quality
calibration bit actually do? If it is something other than setting the white
level, the popup help should probably be changed because that's what it says
this is for. Or maybe it's accurate and my scanner just does a bad job of
it. (which may be why they changed it to driver calibration in the later
firmware versions.) The second question is: Does anyone know another method
of fixing my problem? The problem being basically that white is offscale, and
thus anything near white saturates to white. Any advice would be
appreciated. From looking over the docs and the info reported by the driver,
it appears that the 1220S does not support calibration, lamp adjustment, or
anything of the sort. Let me know if I'm wrong on this. At this point I'm
basically accepting that this all is why I didn't pay very much for this
scanner, and I'll just be happy with it's performance on photographs and
such.
Well, sorry to be so long-winded about this, but thanks for bearing with my
little battle with this scanner and thanks for the great software.
Later,
-Dean Townsley

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