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

[Robert K. <rl...@al...>]

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.

>  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).

-- 
Robert Krawitz                                     <rl...@al...>

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