[sane-devel] plustek backend - "lamp-switch" option

Gerhard Jäger gerhard at gjaeger.de
Tue Apr 16 06:24:06 UTC 2013


On Sunday 14 April 2013 16:03:49 Alexander Hofmann wrote:
> I'm currently playing around with the SANE API. When listing all options
> available for my scanner (Canon N670U a.k.a LiDE 20) I noticed an option
> called "lamp-switch". It provides a description saying it's for
> "Manually switching the lamp(s).".
> Does that mean that the scanner supports scanning with the lamps off?
> (e.g. to scan negatives)?

no. Switching the lamps while scanning is performed by the backend.

> If so, how should I use that option?

This option is available to provide a way for a possible frontend
like XSane for switching on or off the lamp manually for example
before doing a scan. Could be interesting when skipping the warmup
option - which is in fact only useful for CCD based scanner that
hav a CCFL lamp.

> I tried setting it to 1 just bevore starting the scan, but I didn't see
> any changes.
> Also, is there any comprehensive documentation about the various options
> each backand provieds? I checked the manpages, but the "lamp-switch"
> option doesn't seem to be documented there.

You are right. It's in fact not documented, either because I was too
lazy - or it is not useful for command line scanning.

Please don't stick on the "lamp-switch" option. This one is only provided
by the plustek backend. 

Regarding writing a backend, this one could be a starting point

Having a look at the test backend as well.

File include/saneopts.h provides commonly used options, but in
fact it's up to the backend to define which option it provides.

- Gerhard

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