[Openicc] Printing targets: App or driver ? Profiling RGB or CMYK

Kai-Uwe Behrmann ku.b at gmx.de
Tue May 17 08:06:58 PDT 2011

Am 17.05.11, 10:03 +0200 schrieb Jan-Peter Homann:
> Hi Alastair,
> You made a good point. For a smooth step forward, with current available 
> tools and settings (Argyll / Gutenprint), you correct, that profiling in RGB 
> based on a good Gutenprint RGB->CMYK Setting is easier for crowd profiling, 
> which is quite important for the next months.

To me it appears more complicated to need a Rgb profile additional to the 
Cmyk one.

> Question to Robert Krawitz:
> There are a lot of testet Gutenprint settings available, which include the 
> Gutenprint specific RGB->CMYK conversion.
> - Is it possible to create a Gutenprint "CMYK-only" setting by just 
> deactivating the RGB->CMYK conversion ?

Is this the correct level you are looking at? A user sended print target 
will meet Ghostscript on its path. Please do not forget, Linux is 
moving on to PDF. Ghostscript will see GutenPrint can hande Cmyk and 
should normally use that by default. Requiring here Rgb input to pass 
through to Cmyk sounds complicated and to me unpredictable. Will 
Ghostscript use a internal 1-cmyk routine or an other formula or will it 
trigger GutenPrint to use Rgb?

Btw. ArgyllCMS can produce Cmyk targets very nicely.

> - Is it possible to to read easily following parameters from the deactivated 
> RGB->CMYK conversion:
>    - Black generation settings ?
>    - Total ink limit ?
> For stepping into CMYK profiling, this could lead to following workflow
> - read the Gutenprint settings black geneartion and ink-limit for an tested 
> setting

> - deactivate the Gutenprint RGB-CMYK conversion

There is no path for directly accessing this except through bypassing all 
PDF filters by using binary device specific print data. PhotoPrint can do 
this, but not normal applciations.

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

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