QTR-Quadtone RIP

In general, I think most people use the curve shape controls to get the curve "close enough" to linear prior to doing the actual linearization.

If all of the steps have reasonable spacing, especially the lightest and darkest steps, then the linearization curve has to be less severe, and any small errors in reading the samples will have less of an effect on the overall curve.

Think about it, if your darkest 3 steps are 2.02 logD, 2.04 and 2.06, and your densitometer has a +/- 0.01 logD error, it will severely affect the curve shape. But if you can get them to even 0.05 apart using the curve shape controls, that error in reading will have less of an effect.

Of course, it also helps if you read multiple patches (or the same patch multiple times) to help average out those types of errors.

Hope that helps--

Greg

--- In QuadtoneRIP@yahoogroups.com, "wolverinemsu" <bowlby@...> wrote:
>
> I must be missing something in conceptualizing Curve Creation and I can't seem to get my pointy little head around it.  
> 
> I'm making a curve with a single ink (MK or PK on R1800) for matte (MK) or glossy (PK) paper.  In all the tutorials and guides for creating a new curve for a new paper/ink combination, the user is told to set an initial Highlight and Shadow setting of 6 - 10 in the Gray Curve tab.  It seems to me that one should start with these values at 0 (or blank) because during the process of "linearization" any adjustment made to the ink density curve by these settings will be nullified when the linearization factors are introduced folowing densitometry/spectrophotmetry of the gray scale printout.  
> 
> I would think that the linearization should be carried out before tweaking the Highlight/Shadow values, or am I not understanding some fundamental process or concept that QTR uses in generating an ink density curve? 
> 
> Any clarification would be greatly appreciated.
>