[sane-devel] Re: request for extra xsane functionality

[Oliver Rauch]

Hello Jan.

When you scan a DIN-A4 page with 200x200 dpi and save it e.g. as a tiff
file then you get an image with about 1700 x 2200 pixels. At this point
there is no relation to a size in millimeter, centimeter, inch or DIN-A3
or something like that.

What you can do is a pixel based scaling. E.g. you want to reduce the
image with 1700 x 2200 pixel to 850 x 1100 pixel. For this you can use
the viewer mode of xsane:

- select "Viewer" in the main xsane window
- scan the image (no preview, a real scan)
- the image is displayed in the viewer window
- select the scaling function and enter scaling factor 0.5
- when scaling has finished save the image

But there will be nothing like "Scale to DIN-A4", this is not possible
when you do not know the size of a pixel!

Best regards
Oliver




Am Fre, 2005-10-28 um 16.59 schrieb jouthuis at dds.nl:
> Hello Oliver,
> 
> Excuse me for taking somewhat more of your time. I understand your argument
> below, but surely there must be a way around for this?
> 
> For clarity: I'm only discussing the digital image part' of the issue.
> 
> Resolution selection most of the time is a stepped function of 100 dpi. And my
> own scanner can't do anything lower than 200x200. So, at this moment, when I
> scan an A4-original I get a digital image size A3. This I subsequently can scale
> up or down at steps of 1 (with the 'geometry button' at the top of the image
> window). But I can't store a once chosen scale factor, so I have to repeat this
> with every new scan I make.
> 
> Now, I'm not an expert, but I do think that there must be a possibility to
> construct the source code in a way that I can choose a scale factor before I
> make a scan. This scale factor gets stored in memory. Then the scan is made at a
> certain resolution, and after that the 'scale module' (i.e. the piece of
> software behind the geometry button) is activated automatically and fetches the
> stored scale factor from memory to rescale the image accordingly, before it is
> put on the screen.
> 
> I hope the above doesn't sound completely stupid, but I know that Windows
> software can do something like this. And I only want Linux software to be at
> least as good.
> 
> Jan.
> 
> 
> 
> Citeren Oliver Rauch <Oliver.Rauch at Rauch-Domain.DE>:
> 
> >
> > Hello Jan,
> >
> > what you like to have is partly implemented and partly impossible:
> >
> > It means you need to know the size of a pixel of the output device.
> > XSane does know it for printers and so you can select a zoom factor in
> > photo copy mode. When you scan to a file then the size of the image is a
> > width and height in pixels. In this case you have to use the resultion
> > selection to change the size (in pixels) of the image.
> >
> > For Postscript and PDF output and fax mode it would also be possible to
> > add a zoom function. I will think about that. For other pixel based
> > output formats it is not possible.
> >
> > Oliver
> >
> >
> > Am Don, 2005-10-27 um 00.29 schrieb jouthuis at dds.nl:
> > > Preset a rescale factor for the scan(s) to make, which would result in an
> > image
> > > larger or smaller than the original.
> > >
> > > Jan
> > >
> > >
> > > Citeren Oliver Rauch <Oliver.Rauch at Rauch-Domain.DE>:
> > >
> > > > What shall the "rescale-button" do?
> > > >
> > > > Oliver
> > > >
> > > > Am Mit, 2005-10-26 um 12.54 schrieb jouthuis at dds.nl:
> > > > > Hello,
> > > > >
> > > > > I was wondering, would it be an idea to have an extra 'rescale-button'
> > in
> > > > the
> > > > > xsane preview window? Just like the ones for orientation and aspect
> > ratio?
> > > > >
> > > > > With such a button one could save a particular rescale setting and
> > there
> > > > > wouldn't be need to rescale every next scan by hand.
> > > > >
> > > > > Scanning several documents in a row at a certain rescale ratio would be
> > a
> > > > lot
> > > > > more comfortable this way.
> > > > >
> > > > > Tia for your reply.
> > > > >
> > > > > Bye
> > > > >
> > > >