[sane-devel] Looking for information about calibration process

[JKD]

Hello everyone,

I'm debugging calibration process of hp scanjet 3970. But I'm not familiarized
with such process and I'm finding some concepts which are unknown for
me.

Looking at google I've found this interesting post containing some
useful explanations:

http://lists.alioth.debian.org/pipermail/sane-devel/2006-March/016266.html

But I have some doubts yet.

How concepts like adc-offset and gain values are supposed to affect the
final image?. How can they be calculated and applied?.

What's the purpose of black and white shading calibration?. Do both processes
need to be made? (I see that windows driver enables only black shading
calibration in some cases. Why?) Despite the scanner applies by itself such
values, what's the formula to apply them in the final image?

These are just some questions.

Have anyone detailed information about this subject? It could be a good
idea to add links about this subject in "Programmer's documentation"
section of SANE project to help developers to understand the most common
actions that their devices (or official drivers) perform, don't you
think?

Regards,

 Jonathan Bravo Lopez