plustek: Re: [sane-devel] Epson Perfection 1250
Subject:
Re: [sane-devel] Epson Perfection 1250
From:
Reinhard Max ####@####.####
Date:
7 Mar 2002 07:27:01 -0000
Message-Id: <Pine.LNX.4.44.0203070753270.5818-100000@Wotan.suse.de>
Hi,
On Wed, 6 Mar 2002 at 21:11, Gene Heskett wrote:
> and I think at the moment its a combination of a poor calibration
> strip
I don't think that the calibration strip is to blame. I've had a look
at mine. It's just plain white.
> and a semi-cold lamp that didn't have time to adequately warm up,
> something that would effect the color of the ends of the lamp much
> more than the center 90% of it..
I am also not sure that a variation in the lamp's intensity between
center and ends is the main reason.
To me it looks like the color corruption on the borders is due to the
optical system in front of the sensor. The sensor itself is just about
4cm wide and the light is being projected to it via a system of
mirrors and lenses. AFAIK the light throughput of a lens degrades
towards it's border. This gets even worse if the sensor is not
adjusted exactly at the center of the lense. Of course the impact of
this effect reduces as the lamp becomes brighter during warm up. When
my lamp is warmed up for an adequately long time, the color errors on
the borders become much lower, but then the center of the page starts
looking a bit overexposed.
cu
Reinhard
