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

[edmund ronald]

Hal,

 I think there's a consensus that this route exists - and CMYK printing will
be supported in whatever we're cooking up - after all it has been supported
by Gutenprint for some time.
 On the other hand,  I think that making this the primary supported print
path for consumers is asking for trouble.

Edmund

On Tue, May 17, 2011 at 7:55 PM, Hal V. Engel <hvengel at gmail.com> wrote:

>  On Tuesday, May 17, 2011 08:38:11 AM Jan-Peter Homann wrote:
>
> > Hello Edmund and all,
>
> > I support, that profiling for Gutenprint should start based on the
>
> > avilable RGB Gutenprint setups.
>
> > May questions are about possibilities to allow an easier CMYK based
>
> > profiling for Gutenprint in future (no need to prioritize).
>
>
> I have been using ArgyllCMS generated CMYK profiles with my Epson R2400 for
> some time now. These take more effort to create than RGB profiles but when
> done correctly give excellent results. I use PhotoPrint for printing and it
> does the conversion from RGB images to the profiled CMYK printer color space
> and sends the CMYK data to CUPS/GutenPrint.
>
>
> So creating an ICC based direct RGB or any other color space to printer
> CMYK work flow is currently doable but it does require more work to create
> the printer profile and there are a limited number of user level tools that
> support this. I don't see any reason why it shouldn't be possible to do this
> type of thing in a more generalized printing work flow.
>
>
> >
>
> > The main idea behind:
>
> > Gutenprint must handle total inklimit and blackgeneration if it can be
>
> > driven with RGB-data.
>
> > If we have working Gutenprint settings, we may could use the information
>
> > to configure the Argyll profiler for CMYK based profiling and may be
>
> > also the Argyll target generation (may be necessary for media ink
>
> > combinations with very low total ink limit), .
>
> > In this case, we need special targets, which contain only patches under
>
> > the ink-limit.
>
> >
>
> > But as i said, this needs no priorization and is more interesting to
>
> > color geeks, which e.g. want to compare the results for RGB and CMYK
>
> > based profiling for the same media settings.
>
> >
>
> > Best regards
>
> > Jan-Peter
>
> >
>
> > Am 17.05.11 16:21, schrieb edmund ronald:
>
> > > I don't understand anymore where this is going. Yes Gutenprint can be
>
> > > profiled in CMYK. There are no technical issues, I have done it, any
>
> > > color consultant can do it. No, this cannot be done easily with tools
>
> > > available to hobbyists, and with the current Linux software driving
>
> > > GP, and the quality one gets with the built-in RGB==>CMYK I don't
>
> > > think there is an immediate need to prioritize this route.
>
> > >
>
> > > Edmund
>
> > >
>
> > >
>
> > > On Tue, May 17, 2011 at 2:59 PM, Robert Krawitz <rlk at alum.mit.edu
>
> > >
>
> > > <mailto:rlk at alum.mit.edu>> wrote:
>
> > > On Tue, 17 May 2011 10:03:26 +0200, Jan-Peter Homann wrote:
>
> > > > 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.
>
> > >
>
> > > > 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 ?
>
> > >
>
> > > "Deactivate the RGB->CMYK conversion"? I don't understand. If one
>
> > > were to do that, they would get RGB output (or perhaps CMY, depending
>
> > > upon how it's defined; Gutenprint does offer CMY output).
>
> > >
>
> > > Based on the rest of this, are you really asking "is it possible to
>
> > > determine the internal settings Gutenprint is actually using"?
>
> > >
>
> > > > - Is it possible to to read easily following parameters from the
>
> > >
>
> > > deactivated RGB->CMYK conversion:
>
> > > > - Black generation settings ?
>
> > > > - Total ink limit ?
>
> > >
>
> > > No, not at present. I can see API changes that would make it
>
> > > possible.
>
> > >
>
> > > > 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
>
> > > > - Print the testchart
>
> > > > - generate profile with similar settings for black generation
>
> > >
>
> > > and ink-limit
>
> > >
>
> > > > Question to Graeme Gill:
>
> > > > Some Ink / Media Combinations need heavy total ink limits. Is it
>
> > >
>
> > > possible with Argyll to create CMYK-testcharts which are
>
> > > alraedyoptimize for an ink limit and black generation ?
>
>
>
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