QTR-Quadtone RIP

--- In QuadtoneRIP@yahoogroups.com, Ernst Dinkla <E.Dinkla@...> wrote:
>

> In color profiling we expect one printer profile to handle all 
> kinds of images (even B&W) in a far bigger gamut. In this case 
> it is a smaller gamut and it doesn't have to handle color just 
> luminance. The only difference is that we exchange one hue for 
> another to some degree and never extreme. Before the profile 
> creation of QTR was made we used generic matte and gloss 
> profiles, what I propose is a least customised to the 
> individual paper, ink and printer etc used.
> 

Ernst,

You seem more knowledgeable in this then I am, so I hesitate to take 
to strong position here. But I don't think this can work in a general 
sense. You assume that a change of hue has no effect on luminance. In 
reality, a different hue will be realised with a different "sub ink 
set" (e.g. cool vs. warm toners). In general they will need a 
different linearization profile. To me, if their physical properties 
are exactly matched your assumption is true. If that is not the case 
(which is in practice, or at least I don't want to rely on it), a 
change of hue will effect luminance.

Having said the above, I can see how a modification of your proposed 
workflow could work. If you make three curves, one for each primary, 
I imagine one could build a host of different UIs/hue control 
mechanisms on top of it. The ABW for one, the sliders as proposed by 
Roy as another, a color-like workflow as proposed by David Tobie or 
alpha-channels as proposed by Tom. And only three curves is already a 
WORLD of difference, with the infinite amount of curves I would have 
to make now in QTR to get all the hues and split-tones I would like 
to try.

Joost