[sane-devel] Canon LIDA 20 (plustek) scan quality

[Gerhard Jaeger]

Hi,

the pictures are too bright. You need to tweak the threshold
for the binary stuff. This is controlled by the option
--brightness
which goes from -100 (completely black) to 100 (completely white).
The default setting is 0. You might try -20 in your case!

I'll do some checks here.

Ciao,
Gerhard


On Wednesday 12 January 2005 02:41, Alvaro Figueiredo wrote:
> At Tue 11 Jan 2005 06:25, Gerhard Jaeger wrote:
> > Hi,
> >
> > On Tuesday 11 January 2005 05:41, Alvaro Figueiredo wrote:
> > > Hi, all.
> > >
> > > I recently bought a Canon LIDA 20, a USB scanner. It readly
> > > worked on my Linux 2.6 box, but its scan quality is really much
> > > worse than Windows 98 driver's scan output. It is a dual boot
> > > box.
> > >
> > > I am scanning regular text documents, like the sample bellow.
> > >
> > > scanimage --resolution 300 --mode Binary -x 210mm -y 297mm
> > >
> > > The Windows output is almost perfect, like a photocopy. The
> > > sane's output seems to have much less resolution and misses
> > > some portions of text that is not black. I am using the same
> > > mode (lineart) and resolution (300dpi) on Linux / sane and
> > > Windows. I can send both outputs, if anyone request it (near
> > > 150k each, in PDF).
> >
> > please send it to me.
> >
> 
> I made available three documents scanned on Linux (sane) and on 
> Windows (manufacturer's driver). They are doc1???.pdf, doc2???.pdf 
> and doc3???.pdf (??? is lin or win). I did ran a sample with debug 
> enabled and published it all at:
> 
> http://alvarof.freeshell.org/sane/
> 
> > > I have no scanning experience, but I had tried almost all
> > > options of scanimage without significative improvement.
> > >
> > > Am I missing something, here?
> >
> > Probably not.
> >
> > > Follow some system information.
> > >
> > > scanimage --version
> > > scanimage (sane-backends) 1.0.14; backend version 1.0.14
> >
> > you might update to 1.0.15.
> >
> 
> My Linux distro uses RPM, and I already keep it updated. I will try 
> upgrade sane later on, with alternative packages.
> 
> > > scanimage -L
> > > device `plustek:libusb:001:004' is a Canon N670U/N676U/LiDE20
> > > USB flatbed scanner
> > >
> > > sane-find-scanner
> > > found USB scanner (vendor=0x04a9 [Canon], product=0x220d
> > > [CanoScan], chip=LM9832/3) at libusb:001:004
> >
> > Could you please to the scan again, enabling the debug output,
> > and send me that too? export SANE_DEBUG_PLUSTEK=20
> >
> > Ciao,
> > Gerhard
> 
> I did not scanned color pictures yet. I do not know if it presents 
> some anomaly.
> 
> Please, let me know if I may help you with more information or if I 
> could make more tests.
> 
> Thank You by your attention.
>