QTR-Quadtone RIP

I'd like to think I'm wrong, but I don't believe there's any shortcut to 
curve creation.  For example even if you only change the shadow density 
on the grey tab, all of the ink curves alter, so unless you have access 
to the algorithms which generate the curves you will be at a bit of a 
loss in modeling how a printed step chart would react.  The problem is 
compounded by the fact that every change during curve creation also 
alters the maximum print density, so the each new curve iteration has to 
be compared against a new ideal density curve to see if it's close 
enough to warrant final linearization.  At least, that's my take on it.

I found that keeping careful notes and plotting measured densities 
against ideal densities in Excel for each curve creation iteration was 
the only reliable way (for me, anyway) to produce a final, linearized 
curve.  I also saved time by printing the step chart with several 
combinations of variables in one curve-creation "session".  This used up 
more ink and paper since I was, in effect, creating multiple threads of 
curve creation iterations, with only one being the best one.   It took a 
long time, but I'm hoping that my increasing experience will speed up 
the curve creation process.

What I would like to know is: just how close does a measured-density 
curve have to be to an ideal-density curve before it can be used in 
linearization?

Cheers,

Terence Lowe.