# Re: faint vertical stripes while scanning

Rogier Wolff (R.E.Wolff@BitWizard.nl)
Sun, 8 Mar 1998 22:01:56 +0100 (MET)

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Oliver.Rauch@wolfsburg.de wrote:
>
> Hi Ondrej
>
> > I have just discoverd that when I scan under 300 dpi with my
> > UMAX Astra 1200S I get faint vertical stripes in my image.
> > Sometimes. Moiree Pattern?
>
> Moriee Patterns are only possibly if you scan something that is
> printed. If you take a real photography and the stripes go away,
> I think it is a moiree-effect. If you have this stripes with a
> photograhphy, too, it is not a moiree-effect.
>
> The scanner itself does everything to get the right resolution,
> the driver has nothing to do with it!

My scanner makes a non-faint vertical stripe over my images. I know
the cause:

My scanner calibrates the CCD on a piece of "reference gray" that is
on the bottom (i.e. not normally visible part) of the ruler that is on
the glass plate. Because they put on a little too little glue, the
reference grey is not uniform, and the callibration is "off".

In my case, moving the whole glass plate in the right direction solves
my problem. Of course, this is a problem that the manufacturer should
fix, but I'm lazy & cheap (:I got the thing cheap from a non-local
store).

Roger.

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