Re: [Gimp-print-devel] Strategy for profiling Epson R280 with Ultrachrome K3 inks

[Hal V. E. <hv...@as...>]

On Friday 08 August 2008 02:27:26 pm Robert Krawitz wrote:
> Hal V. Engel wrote:
> > On Friday 08 August 2008 03:36:18 am Marko Milisavljevic wrote:
> >
> > When you generate your profiling target with targen it will be a CMYK
> > target if you are going to create a CMYK profile. You will print it
> > directly to the device through GutenPrint using the same settings as you
> > will use for printing your images in the final printing work flow (IE.
> > all printer driver settings other than paper size and feed options must
> > be the same and so must the paper). You must make sure that
> > ColorSync/CUPS/photoshop do not cause any transformations to occur to
> > the profiling target on it's way to GutenPrint. Since GutenPrint (at
> > least the versions that I have) does not include any cupsICCProfile
> > entries in it's PPDs I would think that you don't have to worry about
> > CUPS causing any issues with this. Since your printer is "customized" if
> > there are cupsICCProfile entries in the PPD you should remove them since
> > these will clearly be incorrect with the new inks.
>
> The CVS repository (and maybe -beta3, I don't remember) does have
> cupsICCProfiles for generic sRGB.

Yes beta3 has these and both have a generic CMYK profile.  Although these 
entries point to files that do not exist on my machine.  In fact to 
directories that will not exist on any Linux machine.   So this needs to be 
fixed.

If these profiles existed on a Linux machine would they actually get used?  If 
so when would this happen and what rendering intents would be used?

Also what is the

*StpPPDLocation: "/usr/share/cups/model/gutenprint/5.2/C/ppd/stp-escp2-
r2400.5.2.ppd"

entry in the PPD for.  This also points to a non-existant file.


>
> >  From my experience CinePaint and PhotoPrint will only print 16
> > bit/channel CMYK files and 8 bit/channel files must be up converted
> > before either of these will accept them for printing. I am not sure if
> > this is a GutenPrint limitation or a limitation in the printing dialogs
> > for these other applications. But I suspect that GutenPrint only accepts
> > 16 bit/channel CMYK files. Robert is this correct? If that is correct
> > then you must make sure that the CMYK files coming out of the device
> > transform are 16 bit/channel. Since you are using 16 bit/channel images
> > this is likely not an issue for your normal work flow. But targen
> > creates 8 bit/channel target images and these will need to be converted
> > to 16 bit/channel before they are sent to GutenPrint. Not a big deal but
> > I though that I would warn you up front.
>
> Gutenprint is perfectly happy with both RGB and CMYK in either 8 or 16
> bits, and you can use the same color correction methods with both bit
> depths (i. e. you can use gamma-corrected 16 bit or uncorrected 8 bit,
> or vice versa).

So this is a PhotoPrint/CinePaint issue then. Ok good to know.