[sane-devel] Re: snapscan & interpolation

Alexandre Abbes al.abbes@laposte.net
Wed, 11 Aug 2004 22:48:57 +0200

Hi I have a snapscan 310, which has an optical resolution at 300dpi.
> Thus the xsane button only proposes resolution up to 300dpi. But I
> know that with a good interpolation, one can scan with this scanner
> up to 1200dpi. Does anybody know how interpolation works? Is it a job
> done by the scanner itself, or a soft post-prossessing that can be
> done with gimp? Any comment welcome ! 

One case that I can imagine is that the scanners' CCD has a resolution
of 300 dpi (=horizontal resolution), but can do motor steps with a
higher resolution (=vertical resolution = e.g. 1200 dpi).(=vertical).
In that case I can imagine that it makes sense to interpolate to
300x1200 dpi.


Thanks for answer bertrik
Ok, I begin to anderstand.
So the interpolation is vertical. The motor does smaller steps, and scans at 300dpi, but with the steps at 1200dpi, there is a soft post-processing to get an image at 300x1200dpi.
Is there any way with sane to tell the motor of the scaner to do smaller steps? I should get then an image 4x longer then the normal one.