QTR-Quadtone RIP

Hi Lou,

>...
>Printing the 21 step grayscale with the straight line 
>profile eliminates the need to print the initial 
>calibration target at 100%. 

Yes.  It's just faster.

>Do you pick the absolute blackest black as read with a 
>spectro for your black Dmax or do you back off a little bit?

I want to be sure there is continuously decreasing density below the dmax
point I pick. I try to pick a point that is at the edge of the "plateau" of
the ink density, even if there is a slightly higher point somewhere on the
plateau.

>I assume that once you have established the black ink limit 
>using this approach, you then print the calibration target 
>(with calibration mode now turned on) at the above determined 
>black ink limit and proceed with partitioning the other inks.

Yes (probably), if I were doing that type of partitioning.  

Note that recently my workflows have not used traditional partitioning. The
1800 3-MK, 100% Eboni workflow (http://www.paulroark.com/BW-Info/R1800.htm)
uses a "staged" beginning of the channels, but all continue with a positive
slope to the same 100% point.  However, this is a very different approach
than one would use with, for example, partitioning of a k3 printer.

The reason I added the "probably" above is that ink densities can probably
be just assumed.  The standard dilution ratio is about 0.3.  That is, each
light ink has about 30% as much pigment in it as the darker one.  The ink
load to density relationship is not linear, however, particularly at darkest
end.  So, the LK is not going to be just 30% of the K.  It'll probably be
more like 35% to 40%.  At the light end it'll be more linear.  That is, the
LLK will probably be about 30 - 33% of the LK.  I wonder if one just took
those numbers and plugged them in if that would be good enough.  Given what
I do to perfect the partitioning curve manually, I suspect I might just
ignore the second calibration curve also.  However, I don't want to confuse
everyone with my initial shortcuts and then additional manual steps that
most will not want to do.  So, most might be best advised to ignore this.

>It also appears you are still trying to stick with QTR default 
>settings for all settings on the Gray Curve and Toner Curve tabs.

Yes.  I think those tabs/controls might be useful to people who are stuck
with curves they can't otherwise alter, but I vastly prefer directly
correcting the underlying curves if there is a problem, as opposed to using
one of these tools.  But, again, if these tools work for people, then use
them.

>... it does get a little complex with so many options and approaches.

Yes.  On the one hand I have tried to simplify, but on the other hand, my
more manual approach to perfecting the curves may just confuse people more.
So, I've been reluctant to talk much about it on this forum.

At the risk of getting too far off the specific subject, I might add that
much of what I've done with the 1800 3-MK approach came out of not only my
desire for the most stable B&W prints but also after seeing many eyes glaze
over as I described profiling, partitioning, toning, Lab color approaches,
etc. to groups of B&W photographers.  I finally just dumped my notes at one
such talk and decided to turn the talk into a focus group session to see
what people wanted.  After doing this with a few groups of traditional B&W
printers and then getting their feedback on the perceived quality of
different types of sample prints I bring to such events, I concluded most
don't want anything to do with all this profiling.  They don't want to learn
the Lab color system - or any color system.  It they wanted that, they'd do
color printing.

I concluded that if black-only printing was acceptably smooth and neutral,
most B&W photographs would do that.  So, I bought an R1800 to see if the 1.5
pl dot would do the trick.  It did -- if and only if multiple channels were
used -- and the R1800 11 x 14 prints are now the bulk of my sales and the
ones I prefer to do.  

With the R1800 multi-channel Eboni MK workflow, all of the profiles use the
same basic, underlying curves.  So, profiling a new paper is a very fast
2-step process -- determine the dmax with a 21-step test print (and a
special profile I put in the package), and linearize.  That's pretty much
all users have to do, and a flatbed scanner is all they need.  Frankly, from
what I've seen in groups of traditional B&W printers, that's about the most
they really want to do.  And, while the people on these forums might be able
to detect a fine grained structure in the test strip midtones, none of the
B&W printers who have seen actual prints, and no prospective customer at the
gallery has every noticed the image structure.  

>I guess no matter how you get there, 
>the key is to get smooth curves and transitions, no unwanted 
>color crossovers or reversals, a linear tone scale, and the 
>best Dmax possible (without getting into unstable territory). 
>Having built some pretty good profiles (with a LOT of iterations) 
>I am looking for a simpler, faster, more effective way. 

See the above.  Join the club.

Then of course, add the frustrations of inevitable ink batch variances, not
to mention less than perfect mixing and dilution, and the reality of having
to re-do profiles starts to get a bit frustrating.  I personally, have found
happiness in an approach that has no transitions, no crossovers, no color,
no mixed inks and no dilutions, but is also the most lightfast and cheapest.


Paul
www.PaulRoark.com