[sane-devel] pixma MP810 working with sane

[Arne]

> Concerning the vertical lines at 4800/2400 dpi for MP810, I'm wondering
> whether:
> 
> - this is a normal behavior of the scanner (which would mean that it has
> to be compensated by the backend), 
> - or if it's an alignment problem of the sensor, the lines corresponding
> each one to a particular sensor cell, but only at high dpi, the sensor
> uses all its cells to scan.
> 
> I think it may be interesting that other MP810 users could give feedack
> on the current CVS backend, if possible, that's why I copy also the
> sane-devel list

Yes I hope we get some feedback, as there was at least one other MP810
user asking for the drivers.
I think it's normal behaviour, but if not, I need to know before the 
warranty runs out!
 
> Do you know if there's an alignment procedure for MP810 ? This is
> usually the case when you get a new scanning device.

There is a printer-head alignment procedure but nothing for the scanner.

> Have you the possibility to test the Canon Windows driver, and see if it
> behaves the same ? 

I borrowed a WinXP laptop and installed the latest drivers downloaded from 
Canon Europe and found that they only support up tp 1200dpi.
If I was a Windows user I would feel very cheated by Canon about this as 
they advertise 4800x4800dpi optical on the tech specs!
In fact I might send a message to Canon support about this and see what 
they say.
 
> Last point concerning the white lines at the bottom: this is simply due
> to the color planes shifting, as the backend algorithm to shift the
> color planes uses only that portion of the image that will contain data
> for the 3 colors. The bottom of the scanned image contains 2 and 1 color
> zones only, due to the color shift. 
> So this is a little limitation for pixma CCD sensors, you must select a
> scan zone a little bit bigger at the bottom, then remove the image
> bottom white zone, that is padded on purpose by the backend to keep the
> image size the frontend expects.

ok I understand, it's not great but I guess there is nothing that can be 
done about it.

Thanks for all the help so far, at least now the scanner is useable from
75 to 1200dpi, which is very good already!
Now I only whish that Mandriva would include the latest CVS in their 
main-backports branch to keep installed packages tidy, but I guess that 
would be to bleeding edge for them.

Best regards,
Arne