[sane-devel] scanimage & epson with gamma correction

Iain Mac Donald iainjunk@freeuk.com
19 Jul 2003 10:03:52 +0100

Hello Henning

Thanks for the info.

On Sat, 2003-07-19 at 07:22, Henning Meier-Geinitz wrote:

> > 
> > When doing this I get the error message
> > 
> > attempted to set inactive option red-gamma-table
> Well, the option is not active :-) When you run "scanimage -h", you
> should get an "inactive" marker after the option. 

The option as listed in the man page is

"--red-gamma-table 0..255,...
        Gamma-correction table for the red band."

Colour correction options do have inactive flags.

> I think "--gamma-correction" must be used before --red-gamma-table in
> the command line. Does "scanimage --help" list "User Defined"  as a
> possible value for --gama-correction?

I had tried the option in lots of positions ;-)
The man page (scanimage --help...) states 

"--gamma-correction Default|User defined|High density printing|Low
density printing|High contrast printing [Default]
        Selectes the gamma correction value from a list of pre-defined
        or the user defined table, which can be downloaded to the

> The argument for the --red-gamma-table is the gamma table itself, not
> a filename. You can generate gamma tables with gamma4scanimage.

I have used gamma4scanimage and a very handy tool it is too. So rather
than referencing a file I have placed the table on the command line
didn't work though. Maybe I need to try a few more combinations.

What confuses me though is it appears that xsane does correct the gamma.
Or is xsane changing the value before showing the picture in the viewer?

Thanks and regards,