Digital BW, The Print

marko.mili schreef:
> I just got a set of UT-14 inks to use on R280 and I'm trying to understand PR's accompanying PDF. It says:
> 
> "Glossy Papers
> The system prints on glossy paper with its midtone, MIS UT type glossy- compatible inks. Because the 100% black is formed with a combination of the C and M inks, Eboni (MK) must not be used. As such, a Photoshop curve, ICC, or QTR must be used to print glossy prints."
> 
> It says "or QTR", implying that ICC and PS curves are meant to use with Epson driver. How can one prevent Epson driver from using K ink by use of ICC profiles or PS curves? I cannot wrap my head around this. Many/most RGB values will be printed by Epson driver using K ink, and it would be practically impossible to work around it, as far as I can imagine. What am I missing? With QTR, of course, it is another story.
> 
> 

Mind boggling it is but Paul did that trick already a long time ago.

K black is used in the Epson driver when enough C,M,Y, reach a value 
that equal components of C,M,Y are replaced by K. That is called black 
generation. If you for example take out C in total then no K will be 
printed. For a simple 4 or 6 ink CMYK printer model and C stays below 
50% it will not trigger K use either, the other inks can then vary over 
a wider range. Black sets only in above 50% CMY. For printer models with 
more K inks, middle grey etc this will only work when C stays below 20% 
or so as the black generation is that long, 20-100%. The dificult part 
is what you have to do with RGB curves to create the conditions on the C 
ink channel. If that is done you can pack the curves in an ICC 
RGB-device profile as David already explained.

-- 
Met vriendelijke groeten,   Ernst


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