QTR-Quadtone RIP

Thanks for that David

Yes it is the Windows version of QTR

The "curve" is shown in Curve Creator when clicking on Show Curve.
This shows both Linearization (a graph from 0, bottom left to 100 top right) and Ink Curves. It is the Linearization graph that is the one I mentioned.

If I enter the values as previous noted, into the Linearization Values panel (Figure 10 of Tom Moore's User Guide)then click Create Curve the result is a Linearization graph from 0, bottom left to 100, top right, of a more or less convex, bowed upward curve.

After printing out the 21step.tif of the resulting Linearization I noted the following result for QTR_1400_UT14_EPSG_cool (measured with the X-Rite 810).

0.09*
0.12
0.17
0.22
0.27
0.32
0.37
0.45
0.52
0.55
0.63
0.72
0.81
0.91
1.01
1.10
1.20
1.34
1.47
1.60
1.78

*0.09 is also the X-Rite 810 standard on the plaque white spot for this Densitometer - in other words the standard "white" - corresponding to EPSG paper "white".

Do these figures seem OK ?   

--- In QuadtoneRIP@yahoogroups.com, "David" <dpgoldenberg33@...> wrote:
>
> 
> 
> Mel,
> 
> > Looking at the curve for the result it doesn't look very linear (David's curve for the IGFS is virtually a straight line).
> >
>  
> I'm not sure what curve you are looking at here. It sounds like you are using the Windows tools, which I am not really familiar with.  Are you referring to curve of measured densities versus step number, or a curve of the ink load versus step number.  (The Mac tools include CurveView utility that shows these curves from the quad files.)
> 
> As I understand it, a plot of density versus step number should have a slight upward curvature, to compensate for human perception. (See the discussion at the end of Tom Moore's User Guide.) The plot of ink load versus step number isn't likely to be linear or have a simple shape, at least in my experience.
> 
> 
> > Not satisfied with this I then printed a further 21step.tif with this file, remeasured the steps and entered these measurements into the Linearization Values of Curve Creator saving this as QTR_1400_UT14_EPSG_cool1.
> 
> I don't think this is what you want to do.  The linearization routine assumes that the measurements represent a print made *without* prior linearization.
> 
>  When I clicked on Show Curve, to my amazement I got a nearly straight line - just a slight wave in the middle. 
> 
> Again, I'm not sure what kind of plot this is.
> 
> The end goal is to get a plot of density versus step number that corresponds to the values in the tables at the end ofTom Moore's guide.  At least that's my understanding, and what I tried to do when I made my curves.
> 
> 
> I hope this helps!
> 
> David
>