Re: was - P700 and P900 full channel support

On 10/31/21 3:17 AM, Oliver Kowalke wrote:
> Hello,
> I've some background in programming and I own a P900 too - how can I support you to get the full
> channel support?

It should be possible to support this, other than the violet channel.  We could support the violet
channel for raw printing (i. e. the user has to do the separations), but actually supporting the
violet ink for normal printing would be a fair bit of tuning work and would need to be hands-on.  If
you're interested in doing this, be prepared to put a lot of time and a fair bit of consumables into it.

The first thing to do would be to look at src/xml/escp2/inks/cmykrb.xml in the Gutenprint source
tree to see an example of what we did for the R1800 and R800, which is CMYK+red+blue (which is
actually closer to purple, but Epson calls it blue).  The most non-standard part of this is the
<Curves> section, which is a set of transfer curves for each ink channel by hue, starting with
blue=0.  I always tested these by printing a rainbow sweep pattern and trying to get as good of a
match as I could with ordinary CMY(K).

My thought about this is that we should at least at first only support the violet ink in raw mode,
as effectively a spot color.