Digital BW, The Print

Paul,

I think an interesting point is that with 6/7 dilutions you are also often
printing with only 3 or 4 inks at once.

Also I find the amount of overlap can have a big impact on print quality.
I find QTR standard partitioning even with 7 ink dilutions can lead to
posterization in the 3/4 tones which goes away if I use a more overlapped
approach like Cone's K7.

Of course then I tend to get a slightly lower dmax as more ink dilutions @
dmax tends to lower it.

In the end the great thing with QTR is that, combined with a linearization
tool, you can do anything you want with the inks and so you can tweak to
optimize any given ink/printer/paper/image if you want.

Cheers,

Mike

On 7 August 2011 15:42, Paul <roark.paul@...> wrote:

> **
>
>
> Michael King <drmrking@...> wrote:
> >
> > ... because of ink position sharing I plan to get
> > "Tri Hextone" such as
> > neutral / sepia / split out of 11 ink positions.
> >
>
> That sounds interesting. The general discussion brings up an interesting
> issue I've found in my experiments with profiling and the use of differing
> numbers of inks and types of profiles.
>
> The dogma is that the more channels of gray ink we have printing, the
> smoother the final print. This dogma is probably a good starting point, but
> my experience is that not only is it characterized by decreasing marginal
> utility, but more may actually be worse in some situations.
>
> With the Epson 1800 and Eboni, in the experiments that ultimately lead to
> the "3-MK" workflow with 3 full strength Eboni channels, I tried all sorts
> of different numbers of channels of that ink. For that printer and approach,
> the smoothest was about 3.5 channels. That is, while subsequent experience
> found that a minority of the 1800 printers needed 4 to be smooth, mine was
> about equal between 3 and 4, and less smooth above that. While the final
> decision to go with a 3-MK approach obviously was influenced by that number
> also allowing color to be installed, I found that more channels did not
> necessarily result in smoother prints, at least with that type of
> arrangement.
>
> Similarly, with a good 1400 and using a channel that does not band (not all
> channels are equal on mine), a single black only can be smoother than the
> 1800 3-MK workflow.
>
> At least with the use of multiple high density inks, as in the 3-MK
> approach, it appears that once enough are employed to hide the banding, the
> use of more channels begins to increase the noise in (roughness of) the
> print. With scanning and digital exposures I'm accustomed to thinking that
> random noise is averaged out with multiple sampling. With printing at least
> with the 1800 3-MK setup, however, noise appears to be additive.
>
> Note that this issue is where multiple channels are firing at the same
> time, not where they are used in a serial partitioning profile. But it does
> raise the issue of whether, using multiple overlapping channels will always
> lead to a smoother result.
>
> While I've been a fan of making profiles with more overlaps in them, with
> my 7800 I tested profiles with overlapping, dual channels, using QTR, and
> found the smoothest was the single, serially-partitioned profile -- the
> standard, simple QTR all-gray (no "toners") profile, made using Roy's
> semi-automatic partitioning algorithm.
>
> It may be that there is a trade off between hiding banding and increasing
> noise in the system. Also, I think there is an issue of the tolerance of a
> profile to inconsistent papers and inks, and that issue probably favors more
> channels firing at the same time.
>
> Overall, there seem to be a lot of different issues that affect our
> printing, but it may be that more inks firing at the same time is not
> necessarily a good thing. Noise, including possibly not only the dots but
> the dithering patterns, in our printing systems may, at least in some
> respects, be additive.
>
> Paul
> www.PaulRoark.com
>
>  
>


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