Hi, 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 http://www.sane-project.org/backend-writing.txt 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
