QTR-Quadtone RIP

--- In QuadtoneRIP@yahoogroups.com, Howard Shaw <glassman@...> wrote:

> I don't therefore understand the Dmax results you are getting. As you 
> suggested earlier using the point list curve input might be worth 
> trying. You could take the visual representation of the curves to 
> approximate your points but then just alter the LK slightly so it 
> doesn't come in until say 90%.

Howard, 

It is true that the light inks are at 0 at 100% when overlap is set to 
0, but they start coming in right after that.  It seems to be just 
enough to have some impact on Dmax.  

I created a whole series of profiles yesterday on Red River Aurora 
Natural paper (neutral, warm, sepia, cool, selenium).  These are for my 
4000, using MISPro color inks, and I used the plot list to create all 
the curves.  I did precisely as you suggested above, with one 
adjustment.  I started with a previously made, linearized profile 
(using the standard QTR tools).  I duplicated the points in a plot 
list, but I turned off all the light inks at 97% instead of at 100%.  
This gave me back some of the Dmax I had lost previously.  My 
adjustment was as follows.  My ink limit for this paper is 85%, so I 
multiplied all the points in my curves by 100/85 (1.18), so my plot 
list would be based on 100% ink limits.  Then by telling QTR that my 
default ink limit is 85%, the final plot list curves are automatically 
adjusted downward to match the numbers in the original profile.  This 
method will allow me to use any ink limit up to 100%, and the curves 
will all adjust up or down proportionally based on the default ink 
limit the user inputs into QTR.

This was a LOT of work initially, but I am hoping (perhaps foolishly) 
that it will allow me to migrate these curves to other papers and 
simply select the appropriate ink limit and relinearize.  If it works, 
it will be very fast and easy to create curves for new papers.  I am 
also hoping that my toned curves will be much more consistent from one 
paper to another (ignoring the color of the paper base, of course).  I 
haven't created any profiles for other papers yet, but hope to do this 
in the next 2 or 3 days when time is available.  

It would be a whole lot easier if QTR allowed the user to insert a 
negative overlap, or better yet, gave us a chance specify the point 
where light inks dropped to zero (ie, 90%, 95%, 100%, etc).

I'll let you know how things work out when I migrate these profiles to 
other papers.  I plan to try moving them to different matte papers, but 
I also want to see what happens if I migrate a matte profile to glossy 
or luster paper.  And finally, I will try moving a profile from my 4000 
to my 2200 using the same inkset.  Should be interesting.  

Lou