QTR-Quadtone RIP

> > I'm sure that David has nice automatic equipment that may 
> > read the targets patch wise and he started making his 
> > excellent profiles for Epson 9600's with some support from 
> > Epson (read: well calibrated printers). Not linearising with 
> > a  manual Spectrocam the customised Epson 9000 made for dye 
> > inks loaded with third party quad inks :-)
> 
> Busy day yesterday. Bill its should be.

Ernst, the idea of multiple linearizations is different from tracking 
printer instabilities and/or reading errors. Your points are all 
valid but imho do not tackled the issue I'm referring to.
Linearization is a simple function where you simply swap input-output 
values and get the corrections needed. With a single chanel output, 
probability is high that this simple function will achieve the aim. 
Now with ink split curves and overlaps, I doubt the function remains 
that simple because it's my understanding there's no simple model of 
reversing multiple density outputs due to dot gain, light scaterring, 
overlapping, etc... So sampling iterative adjustments is the best 
option to optimize the output untill you reach the point of tracking 
noise. This is the way linearization is proceeded in commercial 
packages such as Studioprint and this is also what I have experienced 
with QTR : once the output is linearized even on a 51stepwedge I 
don't get a clean linear scale with error above dE 2, read with a 
DTP41 uv-cut in Colorport. Alternative readings with a DTP20-
ColorShop (aka Pulse) deliver the same results and multiple readings 
remain in a dE 0.5 acceptable range after proper drying time.

Anyway, I agree with you that a proper calibration and in the quad 
case, a proper ink split curve shaping is critical. At the time being 
this is my depressing concern, far ahead linearization. I know 
there's a computation to do it but I don't know which. 

Olivier