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

[Alexander Hofmann]

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