[sane-devel] bug with Canon N1240U in Lineart mode at 75 dpi?

[Eric Ding]

Gerhard Jaeger <gerhard@gjaeger.de> wrote:

> you might wanna try and tweak the motor settings, checkout file
> plustek-usbdevs.c and search for MODEL_CANON1200, you will find something
> like:
[snip]
> 		/* Gray mode MCLK settings */
> 		{ 6.0, 6.0, XXX.0, 6.0, 6.0, 6.0, 6.0,  6.0,  6.0,  6.0 },
> 		{ 6.5, 6.5, 6.0, 6.0, 6.0, 6.0, 8.0, 12.0, 12.0, 12.0 }
> 	},
> 
> tweak the settings for "Gray mode" and <= 150dpi (where the XXX is located),
> you may increase the value to 7 or 8...

Well, that certainly improved things!  If I change the value to 7.0 or
8.0, scanning at 75dpi in Lineart now works. It does *not* work if the
value is changed to 6.5.

Eric

> Ciao,
> Gerhard
> 
> 
> > 
> > Eric
> > 
> > Gerhard Jaeger <gerhard@gjaeger.de> wrote:
> > 
> > > Hi,
> > > 
> > > On Saturday 27 November 2004 20:24, Eric Ding wrote:
> > > > I'm using sane-backends 1.0.15 with libusb on Gentoo Linux with a Canon
> > > > N1240U scanner.
> > > > 
> > > > When I try to scan in Lineart mode at 75dpi, I get a few back-and-forth
> > > > pauses, then a significant buzzing sound as the scanner's (green) light
> > > > is on, but the light bar doesn't move at all.  Scanning in other modes
> > > > (i.e., Gray, Color) or in Lineart mode with higher resolutions (i.e.,
> > > > 96, 300, etc.) works fine.
> > > > 
> > > > Scanning with these settings using Canon's Windows driver works, so I
> > > > conclude that this is likely an issue with the SANE plustek backend.
> > > > Below find the stderr output of running
> > > > 
> > > >      scanimage --mode Lineart --resolution=75
> > > > 
> > > > with SANE_DEBUG_PLUSTEK set to 13. Have I found a bug? Can anyone
> > > > confirm or deny this behavior?
> > > > 
> > > > Thanks,
> > > > Eric
> > > [SNIPSNAP]
> > > 
> > > I've tested that here and have no problems so far. It might be, that the 
> > > motor settings for this mode are somewhat at or slightly beyond the limit
> > > so that some devices have no problems while others have...
> > > Can you do some more tests, i.e. increase the resolution and check when it's
> > > working?
> > > 
> > > Ciao,
> > > Gerhard
> > > 
> > > 
> > 
> 
>