[sane-devel] Canon LiDE 90

[Guillaume Gastebois]

Hello,

I need a little bit more informations befor testing (sorry for my poor knowledge
in scanner)

Selon Pierre Willenbrock <pierre at pirsoft.dnsalias.org>:

> I don't know why the image colors are reversed, but it may be worth
> trying to flip the sign bits in Genesys_Frontend. If that does nothing,
> we need to handle that in code(or i am missing some setting of the gl841).
> The other thing you have seen is the half-resolution mode, used for
> greater speed when doing lower(i.E. not full) resolutions.
>

How do you explain yhat with half resolution the image seems to be grayscale and
without it seems to be lineart ?

> > Subsidary question : what is the small white (perhaps black) rectangle
> > in the middle up off page (for calibration) ?
>
> That may be a small metal clamp holding the glass or the calibration
> strip. That is the black(i.E. white) part at the very top.
>
Under this small rectangle I have a vertical more clear line(same height). Is it
because I need to tweek calibration area (without this small rectangle) ?

> To summarize, it is a good idea to have bit 4 on, bit 5 is the half
> resolution switch. I'd put 0x10 into the 0x6c gpio register.
>
> As for the calibration area, you will need to change some code:
> * comment out genesys_gl841.c:4220:(line numbers may differ)
>   status = gl841_feed(dev, 280);/*feed to white strip. canon lide 35 only.*/
> * the same for genesys_gl841.c:4821:
>   status = gl841_feed(dev, 280);/*feed to white strip. canon lide 35 only.*/
>
> then you can try what happens when you turn on the led_calibration and
> the coarse_gain_calibration. offset_calibration needs a bit more
> changes. i think i am having the code needed lying around somewhere.
> essentially, the offset calibration needs to be done with leds off.
> the shading calibration does need even more changes.
>
Where to find led_calibration, coarse_gain_calibration ? How to turn them on ?
For personnal information : what is shading calibration ????

> Additionally, if you can't get the afe to switch the sign, you need to
> do that in the calibration functions(i.E. 65535-value).
>

Only in calibration function ?

Regards
Guillaume

> Regards,
>   Pierre
>