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

[Marko M. <mar...@gm...>]

Hello list,

I have an Epson R280 printer loaded with MIS K4 inks (3rd party
substitute for Ultrachrome K3 inks), without LK and LLK, of course. I
am trying to figure out the best way to profile it. I will probably
use ArgyllCMS for profile generation.

If these inks were standard on this printer, I would treat it is RGB
printer and print patches using "Uncorrected" mode, but that is not
the case. I am thus looking for advice on general approach, so I don't
go barking up too many wrong trees. I imagine I need to do this:
- Print a gradient for each of the 6 inks using "Raw" option to figure
out ink limits for individual channels and where is the crossover
between photo and regular inks. Also print combined inks to figure out
total ink limit.
- Tell Gutenprint about these limits, ideally without recompiling
(simply change settings in driver? modify PPDs or
/usr/share/gutenprint/5.2/xml/escp2/media/something.xml maybe)
- Linearize - not exactly sure how. I see Gutenprint has some HSL
curves in media/something.xml - I assume this is the famed
"linearization"? I don't see how to linearize individual inks or
combinations of inks (M+LM) other then some gamma settings.
Alternatively, print unlinearized with "Density" option and let the
profiling software sort it out (I'm working in 16-bit).

Any hints appreciated.

Marko