QTR-Quadtone RIP

That's my understanding too. Linearization is a one shot deal.  If 
you try linearizing again over a previous linearization, your new lin 
data will overwrite the old lin data, and you will not have a good 
linearized profile.  I also agree that QTR does an excellent job of 
linearization and separation of tones.  

Remember, QTR thinks and works in Lab, so  gamma or dot gain based 
data will look different.  If you open a 21 step grayscale in 
Photoshop (for example in gamma 2.2 grayscale mode) and set your eye 
droppers to read the actual pixels on the left and Lab on the right, 
you will see the Lab equivalents of the K values.  Evenly spaced 
grayscale steps don't equate to the same spacing in Lab.  For 
example, 100K is equal to 0L, but 95K is not 5L, it is 1L.  So, in 
Lab terms, there isn't much separation between these two steps.  If 
that is what you are seeing, then it may be that you are working in a 
gamma or dotgain based working space.  Try working in Roy's Lab 
Grayscale space and see if that makes a difference.

Lou


--- In QuadtoneRIP@yahoogroups.com, Howard Shaw <glassman@...> wrote:
>
> Olivier wrote:
> > When using Linearize-Data figures in the Curve Creator table, the 
> > curves get "re-shaped" so that the output gets more linear.
> > Yet at times, the linearity remains debatable.
> > 
> > Clearing the Linearization Table after, and inputting the 
readings of 
> > the already-once linearized stepwedge should work as an iterative 
> > linearization since the curve are built with the first 
linearization 
> > and the second linearization should refine the output. Right or 
wrong ?
> > 
> I'm pretty sure that's wrong. The curves won't "remember" the old 
> linearisation - they will just be remade with the new one as if 
that was 
> the original.
> 
> I've always found the linearisation process to be uncannily 
accurate. I 
> don't know what calculations are being done but it works very well. 
It 
> helps to have reasonably accurate curve set up in the first place. 
I 
> wouldn't do the linearisation until I had got all the stepwedge 
points 
> within about 10% of where they should be.
> 
> Howard
>