[sane-devel] Colored vertical stripes with Visioneer Xerox DocuMate 510

stef stef.dev at free.fr
Mon Oct 4 04:19:32 UTC 2010

Le Saturday 02 October 2010 19:33:18 chris guirl, vous avez écrit :
> On Mon, Sep 27, 2010 at 12:31 PM, stef <stef.dev at free.fr> wrote:
> >        forgot to check that your scanner was supported by the lexmark
> > backend. Is it the case ? Sometimes scanners are merely relabeled
> > models.
> I don't know. On sane-project.org the model is listed as unsupported.
> I have noticed the other Xerox DocuMate scanners are supported by the
> avision backend. I'm unsure how to find out which backend is being
> used when I run xsane.
> >        Shading correction is varying from backend to backend with the
> > capabilities of the underlying hardware.
> I have thought that it could be the problem you described above - the
> white-calibration area is dirty. However I can't imagine what kind of
> dirt would make this pattern...I uploaded a sample here:
> http://sqrville.org/software/colored_bands.png
> Recently, I was able to make a few successful scans. I can't reproduce
> this now or figure out what made it work and what made it stop working
> later.
> Doing some more testing, I noticed that the scanner has thinner bands
> of discoloration (about half the width of before) at a resolution
> setting of 600dpi.
> It is also worth noting that, to get the scanner working at all, I had
> to add this line to /lib/udev/rules.d/40-libsane.rules:
> # Xerox DocuMate510
> ATTRS{idVendor}=="04a7", ATTRS{idProduct}=="0446",
> ENV{libsane_matched}="yes"
> Chris

	this scanner appears to be supported by the avision backend. I think your 
scans may be affected 'warming up'. When the lamp isn't warm enough, light is 
varying, so scanned data is different other time. This fools shading 
calibration. When the lamp is stable, shading works better.


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