[Openicc] New options on the mainline

[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 :-) ).

   >    > * Color Correction should be set to one of the following:
   >    >
   >    >   + Raw if you want to adjust all the settings manually.  In Raw color
   >    >     correction mode, there will be no automatic correction of any
   >    >     kind, including density adjustment.  If you're not careful, you
   >    >     may find yourself using an excessive amount of ink with this
   >    >     setting.  You will need to adjust the Density control or the
   >    >     controls for the densities of the individual colors.  You may want
   >    >     to use this to establish custom densities and ink limits to
   >    >     achieve maximum gamut.
   >    >   + Density if you want to use Gutenprint's choice of density, but
   >    >     otherwise have no automatic color correction applied.  This choice
   >    >     of setting should be safe (at least in RGB mode; in CMYK mode it's
   >    >     possible for too much ink to be applied).  This is useful if
   >    >     you're satisfied with Gutenprint's default ink limits, but want to
   >    >     adjust the linearization yourself.
   > 
   >    Do "raw" and "density" mode honor user-supplied linearization
   >    curves? Or in other words, which mode do I need to select, if I
   >    want _Gutenprint_ to apply _my own_ linearization (and possibly
   >    channel-splitting) curves, which I supply as parameters? (my
   >    understanding is that this is basically the most desired mode of
   >    operation, at least for CMYK printers, and for CcMmYKk printers
   >    which are not operated in a multicolor mode, but which emulate CMYK
   >    by channel splitting).
   > 
   > Yes, they do honor user-supplied linearizations.  They just don't
   > apply the defaults.

   Is the switch of for the defaults something to decide in PPD's as well?

All of the options work the same way in the GIMP plugin as they do in
PPD files.  The underlying driver, and the option processing model,
are the same in both cases.

-- 
Robert Krawitz                                     <rlk at alum.mit.edu>

Tall Clubs International  --  http://www.tall.org/ or 1-888-IM-TALL-2
Member of the League for Programming Freedom -- mail lpf at uunet.uu.net
Project lead for Gutenprint   --    http://gimp-print.sourceforge.net

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