[sane-devel] Lexmark x1150 works with lexmark backend

[stef]

Le vendredi 1 janvier 2010 14:29:24 Jochen Ehmen, vous avez écrit :
> some additional info:
> 
> The git version is working nicely, but it gets really slow on better
> resolutions.
> (I made an ebuild out of it and installed it as usual - maybe I missed
> some thing there...)
> 
> I then tested using "xscanimage".
> 
> - 75 dpi is quite fast
> - 150 dpi is almost as fast
> - 300 dpi takes about 2 minutes for the whole area
> - 600 dpi takes about 15 minutes for half the area and then hangs doing
> nothing
> - 1200 dpi seems to take forever - I have not waited it through yet
> 
> At 600 dpi (and also on 300 dpi) the lamp is moving forward and backward
> in more and more tiny steps (instead of moving continuously) - slowly,
> slowly creeping through the whole scanning area eventually.
> On "cancel" (because it hangs - see above) it is creeping back in a
> similar way, but faster - doing largerer steps at a time.
> 
> But: it works at up to 300 dpi
> 
> Thank you for now! - I will be here to help by providing any info you
> need to improve it beyound the current state if you want to do that.
> 
> All the best!
> 
> Jochen
> 

	Hello,

	it's nice to see your scanner working. The back/forward motion you see at 
high dpi is called bactracking. It's due to the fact that data is read slower 
than it is produced by the scanner. So it has to wait, and even go back to 
last 'read point' waiting for the computer.
	One way to alleviate this is to compile SANE with libusb-1.0 ( --enable-
libusb_1_0). Another way is to reduced the width (and not hte height) of the 
scan to save USB bandwidth.
	The best solution would be to turn on data compression between scanner and 
computer. But this would involve reversing it, which isn't an easy task.

Regards,
	Stef