QTR-Quadtone RIP

I promised to provide some feedback on building QTR profiles using 
the "Plot List" feature, where you can design your own curves.  Paul 
Roark has been doing this for some time, and I owe him a big thanks 
for all his guidance, both on and off forum.  

I find this method has a few distinct advantages.  Advantages include 
the ability to control every point on any individual curve, including 
where the ink starts and stops.  My original reason for trying this 
method was that I noticed that my finished profiles usually had a 
density loss of 0.03 to 0.05 in terms of Dmax, and I determined that 
this was due to the introduction of light inks in the shadows using 
the standard QTR curves (I am using the MIS Pro color inkset on an 
Epson 4000, so I use LC, LM and sometimes other colors to control the 
tone at different points.  This does not provide the same light 
fastness as pure carbon profiles).  Anyway, a density loss of 0.03 to 
0.05 may not be a big deal on papers with a high Dmax, but it can 
sometimes make a big difference on many of the matte fine art 
papers.  So, I stopped the use of light inks at about 95% and the 
density came back up to the Dmax the MK ink showed on the original 
calibration target print.  Also, by trial and error, I was able to 
create nearly linear profiles prior to linearization, and the final 
linearization simply applied small corrections to make it nearly 
perfect.  The biggest advantage to me is the ability to copy these 
profiles to new papers, requiring only that I set a new ink limit 
(which readjusts all inks in the profile), followed by a 
linearization.  This can also be done with QTR profiles created in 
the standard manner, but this I preferred this approach.

The biggest disadvantage is the substantial time and effort required 
to set up the original set of curves using plot lists, which was 
quite time consuming and a bit tedious.  

<b>(It sure would be nice if we could edit curves on screen by 
dragging and dropping points on the curve or using the arrow 
keys....hint, hint.)</b>

I was originally hoping that I would be able to use my original matte 
profiles (designed for warm toned fine art matte papers) and 
repurpose them for use on luster and glossy type papers too.  Setting 
ink limits and linearization work great.... but.....the PK ink is a 
LOT (and I mean a LOT) warmer than Eboni black, so all profiles 
created for glossy and luster papers from my matte profiles tend to 
be a lot warmer.  

So, I am in the process of creating a set of "Plot List" profiles for 
those papers that use PK ink, (Ilford Gold Fibre Silk, Epson Premium 
Luster, Kirkland Glossy, etc), and will use them as the basis for 
building new profiles on other similar papers.  Just setting the 
paper's ink limit and relinearizing should be all that is required.  

The standard QTR curve shapes work fine and are a lot less work.  But 
the use of Plot Lists can provide extra control where desired, such 
as building a single split tone profile (which doesn't require 
blending two or more profiles). It also allows me to improve Dmax in 
the deep blacks.  You can do nearly anything you want with plot lists 
if you have the time and persistence.

Since I am not using Quad type inksets, I cannot comment on whether 
this approach would show any improvement over the standard approach.  
I suspect there would be less difference, since you are usually using 
3, 4 or more shades of black for the curves, so any "pollution" of 
the deep blacks would seem to have less effect on Dmax, since it 
would be a darker ink to begin with.  Paul or others will be a better 
source of information on that subject.  

As porky pig says....ah-ba-dee, ah-ba-dee....that's all folks!

Lou