[sane-devel] Backend for plustek Opticbook 3600

[stef]

Le samedi 20 février 2010 05:06:40, vous avez écrit :
> On 02/12/2010 08:47 AM, stef wrote:
...
> Hey Stef,
> 
> Sorry I haven't been in touch in a while I have been busy. Ok i've
> looked at this and my understanding is that I have to do two things;
> sort the gain values out and the shading calibration. For the time being
> i am disabling the shading until i have the correct gain values for my
> scans, my understanding is that it will be easier to correct the shading
> once the gain is fixed.
> 
> After trying some different values I find that altering both the gain
> and the gamma colours in the Genesys_sensor has an affect on the
> scanning image. My question is how do I find the correct values for
> them? When i take the fe values for the gain from a snoop they are way
> off, and i dont think i can counter this with the gamma values.
> 
> Also do you know when a next release is likely to happen? Just need to
> know if I have to hurry up with this as i'd like to have it ready for
> the next one.
> 
> Thanks
> 
> Chris
> 

	Hello,

	regarding the gamma values you can extract the gamma tables sent to your 
scanner by the windows driver from USB logs. Put them in a spreadsheet, then 
you can insert the formula used by the genesys backend and compare the 
reference and generated curves.
	For gain and offset, until calibration work I have nothing else to advise you 
than trial and error. But by choosing a black/white target, you may refine 
your tests. Scanned black areas should give values slightly above zero. If no 
raise the offset. Once tweaked, you can adjust gain until white areas give 
values of about 240 (0xF0).
	For the release date I can't tell. Next release should be close. When your 
work should be terminated for your University course ?

Regards,
	Stef