[sane-devel] xsane and large previews

Henning Meier-Geinitz henning@meier-geinitz.de
Sun, 19 May 2002 17:55:38 +0200


On Fri, May 17, 2002 at 10:40:54PM +0100, Major A wrote:
> Hi, I'm trying to use xsane 0.86 with a Nikon LS-8000ED, which is a
> medium-format scanner with a minimum practical preview resolution of
> 1000dpi. This generates huge previews whatever I do.

Maybe the backend should provide a smaller resolution and so do the
down-sampling itsself. E.g. It could use 100 dpi for preview mode.
This also makes network-scanning much faster.

> Now the problem
> seems to be that I use xsane over an ssh tunnel, and it is exceedingly
> slow this way (1 line per second!). Is it possible that xsane wastes
> bandwidth when drawing the preview? I assume it doesn't down-sample
> prior to displaying, I think that would be a good idea.

It looks like xsane starts drawing whenever its buffer is full. If you
use a higher resolution, the buffer is full very fast.

But that's not the only problem. Memory consumption is very big. I can
scan with the test backend with 1000 dpi without problems. But when I
set the minimum resolution to 1000 dpi in test.conf, xsane needs 538 MB
of memory when doing the preview. The image itsself is "only" 35 MB in