QTR-Quadtone RIP

--- In QuadtoneRIP@yahoogroups.com, Howard Shaw <glassman@...> wrote:
> 
> Several greyscale inksets are designed to be compatible with each 
other 
> in this sense. I believe the different positions in the various 
> piezography sets were all of matching density as are the current K7 
> neutral & sepia sets. That is how inks in matching positions can be 
> interchanged and used with the same curves.
> 
> Similarly MIS FS & FSN, the UT7 carbon & cool toners and UT-R2-Warm 
& 
> Neutral all include similar density inks in the equivalent 
positions of 
> the warm & neutral/cool sets. In that sense the luminance should be 
the
> similar whichever way they are mixed & matched.
> 
> Perhaps in this sense, one generic profile would work for each 
family of 
> inks.

You have a point here. I'm not familiar with the K7 sets. The UT7 
carbon and cool toners are supposed to be the same as those of the 
UT3D set. I did not study them in all detail, but if you look to the 
canned QTR curves for these, there are actual slight differences. I 
confess I did not try to take the same settings and compare the 
results. In the ideal case, you and Ernst are right. I just don't 
know how ideal reality is.

> 
> I am not familiar with UT3d which you have been using and it sounds 
like 
> this is a more complex set of inks for which the above scenario 
does not 
> apply.

With the lab a /selenium toner in the UT3D set the situation is 
different indeed.
Unlike for the carbon and cool toners, that each have a LK and a LLK 
version, the selenium toner has just a single LLK version. The LK 
part of the curve has to be built by adding a mix of the cool and 
warm LK toners. Perhaps one could rely on just taking 50% warm and 
50% cool, but I don't see why there is a garantuee that that actually 
results in a linear curve. 

My point is that I sympathize with Ernsts approach, but that building 
the framework on a fundament of three pillars in stead of just one 
would be more robust/accurate AND flexible. One just does not have to 
assume anything, but ane can actually compensate for any 
deviations/peculiarities.

Joost