[sane-devel] CIS scanners: to calibrate or not to calibrate :) this is the question (my scanner is mad and lazy :)

[Rene Rebe]

litlle girl wrote:
> AFE settings looks more stable:
> 
> grep "\[gt68xx\] afe" ./*
> ./color-1.log:[gt68xx] afe 0x0f 0x04 0x10 0x05 0x0f 0x04
> ./color-2.log:[gt68xx] afe 0x0f 0x04 0x10 0x05 0x0f 0x04
> ./color-3.log:[gt68xx] afe 0x0f 0x04 0x10 0x05 0x0f 0x04
> ./gray-1.log:[gt68xx] afe 0x0f 0x04 0x10 0x05 0x0f 0x04
> ./gray-2.log:[gt68xx] afe 0x0f 0x04 0x0f 0x04 0x0f 0x04
> ./gray-3.log:[gt68xx] afe 0x0f 0x04 0x0f 0x04 0x0e 0x03
> ./lineart-1.log:[gt68xx] afe 0x0f 0x04 0x0f 0x04 0x0e 0x03
> ./lineart-2.log:[gt68xx] afe 0x0f 0x04 0x0f 0x04 0x0e 0x03
> ./lineart-3.log:[gt68xx] afe 0x0f 0x04 0x0f 0x04 0x0f 0x04

Aside exposure and AFE the backend probably uploads a
scaling value for each image sensor element (white / dark
shading etc.?) that should be pretty constant.

(And no, I still have not read the genesys backend source
  to verify what it's doing, this is just from other
  educated experience.)

I bet the Windows driver also does not re-calibrate every
scan, at least the Mac driver for the Canon Lide 70 does
only calibrate once after unpacking.

Yours,

-- 
   René Rebe - ExactCODE GmbH - Europe, Germany, Berlin
   http://exactcode.de | http://t2-project.org | http://rene.rebe.name