QTR-Quadtone RIP

On Dec 4, 2007, at 11:29 AM, Louis Dina wrote:

> I promised to provide some feedback on building QTR profiles using
> the "Plot List" feature, where you can design your own curves. Paul
> Roark has been doing this for some time, and I owe him a big thanks
> for all his guidance, both on and off forum.
>
> I find this method has a few distinct advantages. Advantages include
> the ability to control every point on any individual curve, including
> where the ink starts and stops. My original reason for trying this
> method was that I noticed that my finished profiles usually had a
> density loss of 0.03 to 0.05 in terms of Dmax, and I determined that
> this was due to the introduction of light inks in the shadows using
> the standard QTR curves (I am using the MIS Pro color inkset on an
> Epson 4000, so I use LC, LM and sometimes other colors to control the
> tone at different points. This does not provide the same light
> fastness as pure carbon profiles). Anyway, a density loss of 0.03 to
> 0.05 may not be a big deal on papers with a high Dmax, but it can
> sometimes make a big difference on many of the matte fine art
> papers. So, I stopped the use of light inks at about 95% and the
> density came back up to the Dmax the MK ink showed on the original
> calibration target print. Also, by trial and error, I was able to
> create nearly linear profiles prior to linearization, and the final
> linearization simply applied small corrections to make it nearly
> perfect. The biggest advantage to me is the ability to copy these
> profiles to new papers, requiring only that I set a new ink limit
> (which readjusts all inks in the profile), followed by a
> linearization. This can also be done with QTR profiles created in
> the standard manner, but this I preferred this approach.
>
> The biggest disadvantage is the substantial time and effort required
> to set up the original set of curves using plot lists, which was
> quite time consuming and a bit tedious.
>
> <b>(It sure would be nice if we could edit curves on screen by
> dragging and dropping points on the curve or using the arrow
> keys....hint, hint.)</b>
>
> I was originally hoping that I would be able to use my original matte
> profiles (designed for warm toned fine art matte papers) and
> repurpose them for use on luster and glossy type papers too. Setting
> ink limits and linearization work great.... but.....the PK ink is a
> LOT (and I mean a LOT) warmer than Eboni black, so all profiles
> created for glossy and luster papers from my matte profiles tend to
> be a lot warmer.
>
> So, I am in the process of creating a set of "Plot List" profiles for
> those papers that use PK ink, (Ilford Gold Fibre Silk, Epson Premium
> Luster, Kirkland Glossy, etc), and will use them as the basis for
> building new profiles on other similar papers. Just setting the
> paper's ink limit and relinearizing should be all that is required.
>
> The standard QTR curve shapes work fine and are a lot less work. But
> the use of Plot Lists can provide extra control where desired, such
> as building a single split tone profile (which doesn't require
> blending two or more profiles). It also allows me to improve Dmax in
> the deep blacks. You can do nearly anything you want with plot lists
> if you have the time and persistence.
>
> Since I am not using Quad type inksets, I cannot comment on whether
> this approach would show any improvement over the standard approach.
> I suspect there would be less difference, since you are usually using
> 3, 4 or more shades of black for the curves, so any "pollution" of
> the deep blacks would seem to have less effect on Dmax, since it
> would be a darker ink to begin with. Paul or others will be a better
> source of information on that subject.
>
> As porky pig says....ah-ba-dee, ah-ba-dee....that's all folks!
>
> Lou
>
>
> 



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