[sane-devel] Why does XSane set Gamma = 1.0

Oliver Rauch Oliver.Rauch@Rauch-Domain.DE
03 Sep 2004 15:42:38 +0200

I suggest not to do this.

1) Your backend will behave different to all other backends
when you add a gamma value of 1.6 to the backend.
Where is the problem for the user to select a value of "1.6"
instead of "1.0" in the frontend?

2) You add an "intelligence" in the backend that is better placed
in the frontend. The idea of SANE is the separation of frontend and
backend. XSane and all other intelligent frontends already have the
functionallity you need. It is bad to put it a second time into a

If you want to improve the usability e.g. of scanimage, then add an
option to scanimage that generates a gamma table of 1.6, but do not put
it into the backend.

In the moment there are some backends that contain a lot of frontend
functions. This causes very ugly user interfaces and undeterminable
behaviour of the backends.


Am Fre, 2004-09-03 um 14.55 schrieb Ullrich Sigwanz:
> Ok, 
> that makes sense.
> I will proceed as follows...
> I will hold a separate "1.6-gamma-table" that always will be combined with 
> the gamma-tables of XSane (or xscanimage or whatsoever).
> In this case a "1.0-table" will be interpreted as a "1.6-table" 
> (which is a MUST for NIASH scanners to achieve good biasing).
> The editable Gamma-Table will then be more a "correction" than a "setup".
> 1.0 will be a neutral gamma-startup-default which makes perfect sense.
> Regards
> Ullrich