Digital BW, The Print

--- In DigitalBlackandWhiteThePrint@yahoogroups.com, "Tyler Boley" 
<tyler@...> wrote:
>
> I'm still unsure about that. Yes indeed, you can open up the color 
channels based on media 
> performance, and of course linearization has got to be a benifit. 
But it's beginning to look to 
> me like lots of ink makes things more difficult for the profiler. 
I'll know more about this later. 
> So far, the cleanest profiles without problems are coming from set-
ups with very conservative 
> ink levels, individual and total. So are we back to Epson driver 
performance?
> The other thing you can't match is Epson's strange GCR and total 
ink. Somehow they only 
> allow 100% at rgb 000, so only k ink there, but obvioulsy 
considerably more in dark colors. 
> So total ink is "variable". The downside to this is there may not 
be enough color inks available 
> at very dark rich colors like deep browns. You can easily see this 
with a 3d gamut veiwer of 
> an Epson RGB profile vrs a good CMYK profile, it's very skinny near 
K. Then the question 
> becomes, how often do you really miss those colors in the real 
world? Sometimes all of this is 
> just talk.

OK, most of you can tune out now.

You can get pretty close with certain GCR settings, but you need to 
use a profile app. that lets you make a custom GCR curve. Profiler 
and PMP5 both do. Then you need to understand how the curve does what 
it does. I understand how the Profiler curve works, and can get a 
black only output when I send it a grayscale image. Also keep in mind 
that I use one of the neutral black inks. With the warmer Epson 
black, you will of course get some color inks to make it neutral.

As far as ink limits go... There are some tricks that I use with my 
inks, but I don't know if they apply to the Epson inks, so I won't 
spill all that out for fear of causing confusion. Summary is that not 
all inks hit their maximum density in the same place as their maximum 
chroma. You need to find a good balance between those two values. 
With the rather different inks that I use, you also do not want to 
run the light cyan all the way down to the maximum full cyan as it 
takes away from the blue coverage. The secondary and tertiary (if 
present) ink limits can have a huge effect on the gamut. And then you 
add in the 2 color and 3 color limits, as well as the 4 color limit. 
As far as the skinny near black gamut, that would be your 2 color and 
3 color limits (for the most part). You have a lot less control with 
those limits, since they seem to be a spill over limit of sorts (at 
least with the Evolution RIP).

I purposely kept all this pretty generic so some people that are 
mildly interested would follow things, there is way more detail that 
I could add, but it gets a little complex, and really needs a bunch 
of graphs to support it. I had to learn a very large amount to get 
the inks I'm using to work properly, you learn a lot when the inks 
and printer are not matched. Now I feel that I can get just about any 
configuration to work (if the RIP allows me the control needed), and 
that includes multiple light inks mixed to a single channel where 
there is no "automatic" guidance to mix them. Understanding how the 
RIP is doing it's job is very important, and often the only way to 
know this is to make many different configurations to see which one 
works best. It can be a slow process where gains can be very small.