Re: [Gimp-print-devel] Advice on how to add the Epson SL-D700

[Solomon P. <pi...@sh...>]

On Sun, Aug 08, 2021 at 09:49:03PM -0400, Solomon Peachy wrote:
> Since that value needs to be specified in terms of base_res * 2, which 
> varies based on the print resolution. it either needs to be specified in 
> resolution-independent units (and get converted) or has to be pushed 
> made into a <resolution> parameter.  Which is your preference?

I have it currently specified in units of base_separation (ie 360).  All 
resolutions now function properly, so I've moved on to trying to tune 
this thing a bit better, but there are a lot of knobs:

 * Inks:  relative intensity of sub-channels
 * Model: density & dropsizes (per-resolution)
 * Media: density, subchannelcutoff, YMCbalance, gamma, Ktrans/GCR, HSV maps
 * External: ICC profile

If I understand correctly, the drop sizes are specified relative to 
"largest possible" so presumably one would tune the overall 
model/resolution density until the media is sufficient saturated, and 
from there tune each successively smaller drop size until the output is 
sane. From there you'd add in the subchannels (eg light C/M in this 
case) and adjust their relative intensity until things look right.

Then you'd fine-tune the different media types for color balance, 
relative density, and whatnot. Subchannelcutoff and gamma being the most 
interesting.

Is all of this ultimately a matter of (systematic) trial and error?
Am I on the right track here?

Lacking any better idea, flipped a coin and used the pro_ultrachrome.xml 
CcMmYK ink and pro_ultrachrome.xml media definitions as a starting point 
(which IIUC are printhead-independent) Should I have used 
f360_ultrachrome.xml (or one of the many ultrachrome_* variants) instead? 

(I noticed that the pro_* stuff seems to have a 1.0 gamma where the 
 f360_* stuff seems to have a 0.92 gamma..)

For the resolution-specific density/dropsizes, I started with the 
pro_x600 baseline which turned out to be quite wrong but I guess I had 
to start somewhere...

 - Solomon
-- 
Solomon Peachy			      pizza at shaftnet dot org (email&xmpp)
                                      @pizza:shaftnet dot org   (matrix)
High Springs, FL                      speachy (libra.chat)