Digital BW, The Print

--- In DigitalBlackandWhiteThePrint@yahoogroups.com, "Greg" <dfaprinting@y...> wrote:
>
> --- In DigitalBlackandWhiteThePrint@yahoogroups.com, "Roy Harrington" 
> <roy@h...> wrote:
> > I have two suspicions on the issue.  First, is just that the large 
> number of inks
> > puts a more critical burden on all the transitions from ink to 
> ink.  Since there are more
> > transitions and they happen more steeply.  The other is the 
> variable dotsize transitions.
> > This isn't an issue for the 2200 at 2880dpi but does show up in 
> 1440dpi.
> 
> Roy, couldn't you just set the dot size to the smallest dot and let 
> the dither pick up all the rest of the work? I know on most of the 
> commercially available color RIPs this is an option. This is the 

Well if you have the smallest dot, at 1440x720 even if you fill every position with
ink  you can't get enough ink for a real black.  With 4pl drops you need to use a
2880x1440dpi resolution to get enough ink on the paper.   This is why 2880 can
use just one drop size.   It might be interesting to try the next larger dot which
would cover at 1440x720.  Ordinarily this would show dots but with the K7 inks
that wouldn't be a problem.

> trick that people use to get the finer quality out of a 76/9600 when 
> using the 1440 or 720 faster print modes. If not then you might need 
> to do a linearization for each dot size, and then all the other 

The thing about different dot sizes is the "dot gain" on the paper.  This is where a drop
of ink spreads out slightly.  But it depends on both size of the drops and number of
drops.  So even when you make a smooth dotsize transition with one ink when you
add other inks the new drops affect the original transition.  The idea is to make
the transitions wide enough the you can smooth them out with linearization.

Roy

> programming involved to switch between those different maps, which is 
> another thing that some of the color RIPs will do.
> 
> As far as the ink to ink crossovers go, I can't offer any help with 
> that since I don't run that kind of system. I will say that sometimes 
> I find it helpful to graph out the linearized densities on paper, and 
> then make the curves for mixing on paper. Don't know if that would 
> help or not, and again my experience is mostly for color ink mixing.
> 
> In the end, based on what you have already seen between the different 
> dot sizes, I'd lean in that direction first with either a fixed dot 
> size, or with seperate linearization tables for each dot size (which 
> sounds really easy when typing it, but I bet it's not so simple to 
> program).
>