[sane-devel] manual "exposure time" in Genesys Backend

Stef stef.dev at free.fr
Sat Sep 26 16:33:12 UTC 2015

On 21/09/2015 22:01, Alexander Hofmann wrote:
> Hi,
> I'm currently playing around with the genesys backend, trying to force
> the scanner to over-/underexpose the image. The backend already has the
> option to switch the lamp off; I'd like to use that feature to scan
> arbitrary translucent/projected images - but I would have to control the
> exposure time.
> I'm a bit confused of the various calculation steps needed to calculate
> the "exposure"; if I simple overwrite the exposure_time calculated
> during scaning to a custom value, the head moves slowly but scans only a
> small portion of the image.
> I looked into the datasheet of the Genesys GL841 chip; I guess the "line
> peroid" setting is the right thing to change, but it seems this is also
> linked to the motor driving unit?
> I realize this is probably a silly question and an absolutely
> non-standard usecase, but maybe someone on the list can still help?
> Anyway..
> thanks in advance,
> Alexander

     have you tried to tweak genesys frontend's analog gain ? Exposure 
is also related to motor speed, and will be really complicated to set up.


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