# Re: I need Help???

becka@rz.uni-duesseldorf.de
Wed, 6 Jan 1999 14:00:07 +0100 (MET)

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Hi !

> I need to modify a flat bed scanner to scan upto a 1 metre lenght at 600dpi.

Oh ... I suppose you know about the mechanical implications of that task - right ?

> Is it possible to use SANE to give the necessary low level instructions to
> the scanner or would it have to be down through the eprom controler?

At least the Mustek scanners used to happily go beyond physical limits,
if asked to do so by the software.

I don't know, if it lasts for one metre, but the scanner wagon crashes into
the end of the rail, if the length given is too long.

You just need to modify a const in SANE to allow that.

Also make sure you get a scanner, that moves the optics as a whole.

Some models are known to have the CCD at the back and use some clever
system of guiding wires to move a 45 degree mirror and the focussing
optics under the tray.
This would probably be very hard to extend to 1m.

> Do modern day scanners position by stepper motor counts or some other means?

I'd say so. though the microcontroller usually takes care of the stepping
itself.

> Where is the auto calibration functions coming from?

You mean the alignment of the three colours ? depends. Some do it in the
scanner, some after transmission.

Or things like AccuPage ? I.e. auto-adjusting brightness/contrast ?

These are often done in software. You scan a bit, analyze it, and tell the
scanner to adjust its gain/offset.

CU, Andy

    --
    Andreas Beck              |  Email :  <Andreas.Beck@ggi-project.org>

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