QTR-Quadtone RIP

Duane,

Now we're talking heuristics:

1.  Default Ink Limit when density increase < 0.03.

2.  Black Boost no more than 1.15 x Default Ink Limit.

As it happened, my values for Moab Kayenta Matte were very close to
those suggestions.  So, in the spirit of exploring other variables, I
tried systematic variations for both warm and cool curves with most
combinations of:

1.  Shadow = 6, 12, 18, 24, 300 (maximum allowable).
2.  LK Limit = Default (045), 036.

Best dMax AND shadow detail, for both warm and cool, popped out for:

1.  Shadow = 300.
2.  LK Limit = 036.

So, the next round will hold Shadow = 300 and vary LK Limit (040, 030,
025, 020).  Will report back soon.

   


--- In QuadtoneRIP@yahoogroups.com, "dlruckus" <dlruckus@...> wrote:
>
> --- In QuadtoneRIP@yahoogroups.com, "milogiacomorambaldi47"
> <milogiacomorambaldi47@> wrote:
> >
> > I'm still looking for heuristics for selecting the best Default Ink
> > Limit.  This seems to be an important first step, but the best
> > approach seems unclear.
> > 
> 
> Milo (?), I don't know about heuristics but this is what I do.
> When the transitions on the initial 100% calibration print cease to be
> at least 0.03 density ( or approx 0.075 Lab L*), I select that or the
> previous step as the default limit and reprint the calibration chart
> with it. For me, doing it that way has always prevented the error
> problems in linearizing the curve later on. If you have the
> measurement tool, I would use it's #s rather than visual estimates.
> 
> > 
> > "Reprinting the ink separation page, limited to 50 this time, I could
> > see PK transitions up to 75 - but no further. 
> 
> You can leave all inks at the default limit ie: don't put any value
> into the separate limit boxes for each ink, but you don't have to. You
> can use different limits for each ink. Whatever you put in those boxes
> will over ride the default, is my understanding. I don't know if
> limiting the lighter inks a lot more than the default will impact
> smoothness of results or not but I think it is likely that it would.
> 
> What I am wondering is why you aren't seeing transitions farther up
> the scale with the PK. Where was it on the initial 100% limit
> calibration print? I would be tempted to limit it a bit more than the
> default for K until it transitions better or just lower the default
> limit a bit more.
> > 
>   Regardless of
> > whether I set Black Boost to 55, 60, or 100...
> > 
> 
> Roy has stated several times that you should not use more than 110 to
>  115% of default limit for your boost value. As you have noted it only
> is supposed to impact maximum K ink.
> 
> >
> > Two questions:
> > 
> > 1.  Do matte papers typically exhibit this behavior compared to
> > glossy?  I've only done one of each, so I really don't know.
> > 
> > 2.  What about the Gray Curve tab?  So far, I've always left Highlight
> > = Shadow = 6.  Is it worth increasing Black Boost (even to 100) to
> > regain dMax and then increasing Shadow (10? 20?) to lighten the bottom
> > transitions?
> >
> 
> Papers can and do vary quite significantly for both types.
> 
> I would first get a good feel for what is needed with regard to
> limits,boost and the relative densities of the K & LK inks before
> adding more variables to the equation. See that overlap is 0 to keep
> d'max as high as possible also. After you have a nicely transitioned
> 21 step scale and can linearize it without trouble, is the time to go
> back and play with the different variables to see what they actually
> do IMHO.
> 
> Regards,
> Duane
>