[sane-devel] unpaper default parameters

[Jens Gulden]

Hello,

Peter Fales wrote:
> I get white pages as output on my i686 machine unless I use 
> --no-border-scan.   I haven't analyzed why - and I'm not sure whether
> running unpaper with all default arguments is even expected to work.

You're right, the default parameters are NOT expected to always work
out-of-the-box. It depends on the input image whether they make sence or
not. All of my own tests have been made on grayscale paper scans with
"good" contrast, directly originating from scanadf, size 1648 x 2337 pixels.

Could it be that your scans are too bright, so that the automatic
border-scan treats all pixels as non-black pixels? What happens if you
use different values for --black-threshold or --white-threshold? What if
you set a --border-scan-threshold even lower than the default of 5?

Are you specifying the --layout parameter, setting it either to 'single'
or 'double'? (Most of the automatic processing makes sence with a
specified --layout only.)

Please anybody let me know which default values would make more sence
for unpaper.

Jens