[sane-devel] Scanning Lineart/Halftone with MICROTEK Scanmak
Oliver Rauch
oliver.rauch@rauch-domain.de
Fri, 24 May 2002 17:27:34 +0200
Hello.
I did some tests with xsane-0.86 (save and viewer) and the pnm backend in
lineart mode some time ago and was not able to find any problems. I would
be glad to help if I can reproduce the problems. What I need is an exact
description under which conditions the image is sheared .
The automatic area dection tries to find out if the background is black or white
and searches the first pixels that are not of the background color.
In grayscale and color mode there is threshold defined in xsane so that
e.g. a bright gray is seen as a whit background. When scanning a lineart image
then one single pixel that is not of the background color defines the area
of the image. Make sure that the background of the scanner is clean.
Bye
Oliver
Karsten Festag wrote:
>
> Joachim Backes wrote:
> >
> > Hi, Karsten,
> >
> > On 16-May-2002 Karsten Festag wrote:
> > > Hi Joachim,
> > >
> > > the function that finds the scanning area and calculates the
> > > dashed rectangle is included only in xsane if I'm not wrong.
> > > That's why in xscanimage you have to draw the scanning area
> > > by hand. I don't know the way xsane calculates the scanning
> > > area but it might be an issue of the contrast between the
> > > sheet of paper and the background of your scanner lid. Maybe
> > > a black paper as background does the trick?
> >
> > The cover of the scanner IS black!
>
> Hmm, in this case the black paper probably won't help ;-)
> Anyway, I think Oliver Rauch should make a statement if it
> could be a xsane problem.
> I think it isn't backend-related because the preview-image
> seems to be correct.
>
> >
> > >
> > > There were some reports of garbled xsane lineart scans
> > > earlier, perhaps Oliver Rauch knows something about this?
> > > I tested this with my scanner: If you scan into a file or
> > > for a fax or for photocopy then the pictures are o.k. as
> > > well as the preview. Only the viewer makes problems. Is this
> > > the same at you?
> >
> > Almost. Additionally, when scanning into the viewer, not only
> > the viewer picture itself is blurred or shaked, but the file's
> > contents too when saving the picture to some file.
>
> Same as above - looks like an xsane issue only for the xsane
> viewer mode. Oliver, do you agree?
>
> Karsten
>
> >
> > Regards
> >
> > Joachim Backes
> >
> > --
> >
> > Joachim Backes <backes@rhrk.uni-kl.de> | Univ. of Kaiserslautern
> > Computer Center, High Performance Computing | Phone: +49-631-205-2438
> > D-67653 Kaiserslautern, PO Box 3049, Germany | Fax: +49-631-205-3056
> > ---------------------------------------------+------------------------
> > WWW: http://hlrwm.rhrk.uni-kl.de/home/staff/backes.html
> >
> >
> > >
> > > Regards,
> > >
> > > Karsten
> > >
> > > Joachim Backes wrote:
> > > >
> > > > On 06-May-2002 Karsten Festag wrote:
> > > > > Hi Joachim,
> > > > >
> > > > > I will investigate this, but as I have no time in the moment it will be
> > > > > not before next week.
> > > > >
> > > > > Does the same problems occur with xscanimage?
> > > >
> > > > Hi, Karsten,
> > > >
> > > > using xscanimage:
> > > >
> > > > 1. When using pre-view with xscanimage, then the dashed preview rectangle
> > > > totally misses after prescan. I have to draw it myself.
> > > >
> > > > 2. The shake-effect together with xscanimage using lineart or halftone
> > > > is heavily reduced (there is a little effect: letters have a small
> > > > black-pixeled wreath which lets letters to be blurred).
> > > > No problem when scanning in gray or colored mode.
> > > >
> > > > Regards
> > > >
> > > > Joachim Backes
> > > >
> > > > --
> > > >
> > > > Joachim Backes <backes@rhrk.uni-kl.de> | Univ. of Kaiserslautern
> > > > Computer Center, High Performance Computing | Phone: +49-631-205-2438
> > > > D-67653 Kaiserslautern, PO Box 3049, Germany | Fax: +49-631-205-3056
> > > > ---------------------------------------------+------------------------
> > > > WWW: http://hlrwm.rhrk.uni-kl.de/home/staff/backes.html
> > > >
> > > > >
> > > > > regards,
> > > > >
> > > > > Karsten
> > > > >
> > > > > Joachim Backes schrieb:
> > > > > > Hi,
> > > > > >
> > > > > > having problems with Microtek ScanMaker 96000 xl.
> > > > > >
> > > > > > Environment: Linux RedHat 7.2
> > > > > > Kernel 2.4.18
> > > > > > xsane-0.86
> > > > > > sane-front/backend-1.0.7
> > > > > >
> > > > > > 1. The preview: When previewing a A4 Page with normal
> > > > > > text on my ScanMaker 9600xl
> > > > > > (A3 scanner), then after previewing, the dashed frame
> > > > > > painted around the read
> > > > > > page is not correct: horizontally, the frame correctly
> > > > > > stops at the right margin
> > > > > > of the A$ page, but the lower margin does not stop at
> > > > > > the bottom of the A4 page,
> > > > > > but at the bottom of the Scanners A3 pane. That means,
> > > > > > the preview frame contains
> > > > > > the rectangle u,v,w,x and not u,v,y,z
> > > > > >
> > > > > >
> > > > > > u v
> > > > > > +-------------------------+---------------+
> > > > > > | | |
> > > > > > | | | A3 Pane
> > > > > > | | |
> > > > > > | | |
> > > > > > | | |
> > > > > > | A4 sheet | |
> > > > > > | | |
> > > > > > | | |
> > > > > > | | |
> > > > > > | | |
> > > > > > | | |
> > > > > > | | |
> > > > > > | | |
> > > > > > | | |
> > > > > > | | |
> > > > > > | | |
> > > > > > | | |
> > > > > > | | |
> > > > > > | | |
> > > > > > | | |
> > > > > > +-------------------------+ |
> > > > > > |y z |
> > > > > > | . |
> > > > > > | . |
> > > > > > | . |
> > > > > > | . |
> > > > > > | . |
> > > > > > | . |
> > > > > > +-------------------------+---------------+
> > > > > > w x
> > > > > >
> > > > > > 2. Having problems when scanning in LineArt or Halftone
> > > > > > mode: in the scan,
> > > > > > a lot of horizontal pixel lines are shifted against
> > > > > > each other, so you have a
> > > > > > "shaked" not readable picture.
> > > > > >
> > > > > > Scanning in Grayscale/Color mode is OK.
> > > > > >
> > > > > > Regards
> > > > > >
> > > > > > Joachim Backes
> > > > > >
> > > > > > --
> > > > > >
> > > > > > Joachim Backes <backes@rhrk.uni-kl.de> | Univ. of
> > > > > > Kaiserslautern
> > > > > > Computer Center, High Performance Computing | Phone:
> > > > > > +49-631-205-2438
> > > > > > D-67653 Kaiserslautern, PO Box 3049, Germany | Fax:
> > > > > > +49-631-205-3056
> > > > > > ---------------------------------------------+----------
> > > > > > --------------
> > > > > > WWW: http://hlrwm.rhrk.uni-kl.de/home/staff/backes.html
> > > > > >
>
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--
Homepage: http://www.rauch-domain.de
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xsane: http://www.xsane.org
E-Mail: mailto:Oliver.Rauch@rauch-domain.de