[Openicc] New options on the mainline

[Kai-Uwe Behrmann]

Am 20.01.08, 11:28 -0500 schrieb Robert Krawitz:

>    Date: Sun, 20 Jan 2008 09:54:48 +0100 (CET)
>    From: Kai-Uwe Behrmann <ku.b at gmx.de>
> 
>    Am 19.01.08, 19:31 -0500 schrieb Robert Krawitz:
>    >    Date: Sun, 20 Jan 2008 01:19:04 +0100
>    >    From: Gerhard Fuernkranz <nospam456 at gmx.de>
> 
>    >    I'm wondering, whether user-supplied
>    >    channel-splitting/calibration curves, i.e. Cyan input => Dark
>    >    Cyan and Cyan input => Light Cyan, wouldn't provide more
>    >    flexibility for the user to establish an arbitrary blending
>    >    between the dark and light inks? I guess that such curves
>    >    would also make 2) 3) and 4) obsolete?
>    > 
>    > Yes, although it would be more complicated to implement.  If it
>    > turns out to be really necessary, we can look at it then.  Of
>    > course, someone else might want to go ahead and implement it :-)
> 
>    IMO linearisation, like the above ones, can be easily created as a
>    linearisation Device Link (DL) ICC profile with just the according
>    curves and of course with no n-channel table corrections. A
>    belonging curve editor could then simply implement a pair wise
>    curve editing for light / dark inks. Some additional sliders int
>    the UI to set start/end points or a gamma to start with would be of
>    help. The values resulting from the slider must only be mirrored
>    for the ligth/dark channels respectively.
> 
> Right, and then use the Raw or Density color correction methods.  That
> would simplify a lot of things (from the Gutenprint side, at least :-) ).

Hmm. Many people, including me, simply used the default linearisation - 
the inbuild from Gutenprint. Well, after someone takes such a project 
sucessfully on her/his shoulders, all other modes could be marked non 
colour management stable. Then you could do what you like with them (tune, 
improve). 

As long as no one puts his hands on such a calibration tool it would be 
wise, as you already stated, to keep at least Uncorrected in a most colour 
stable state.

About exporting the current calibrations:
from the previous post I'd guess most parts are already somehow available 
through a interface. How much work would it be to make a small tool to 
export the Uncorrected curves to something readable? I could help on 
transforming say integer or double arrays to the above mentioned DL 
profiles inside such a tool. With the tool, I'd guess, the Uncorrected 
mode is not that much desired to keep stable across releases. Uncorrected 
still remains as a good starting calibration.
The created DL profiles would not at all know about device states. So this 
part remains open. I would later connect this as well, i.e. make the DL 
knowing about the Gutenprint options.

With the DL's I hope existing profiles, based on Uncorrected, will work 
in Gutenprint 6.0 too :-)

kind regards
Kai-Uwe Behrmann
--
developing for colour management 
www.behrmann.name + www.oyranos.org