QTR-Quadtone RIP

Tony

In the qidf file (or in the QTRgui Curve Creation page) the ink
densities are all expressed as a percentage of black. In his original
notes for QuadtoneRIP, Roy suggested that each black ink be measured
relative to the next darker black ink and then the percentage of black
be calculated.

For example suppose LLK had 20% the density of LK, and
                    LK had 40& of the density of K
then LLK has 8% (20% of 40%) of the density of K

The reason Roy originally suggested this method (I think) was that he
was simply using his eye to compare patches and estimating where in
the 5% step between patches the lighter ink fit. With a densitometer
it is probably just as easy (and accurate) to measure each grey ink's
density relative to K directly.

With regard to what inks to compare, your best bet is to look at some
existing UT7 curves to see how the inks are used. Make sure you look
at curves for the type of paper (matte or glossy) you are planning to
use. Also, the use depends on the type of K ink you are using. For
example curves for an inkset using PKN as the K ink would be different
than those for an inkset where the K is Eboni. Since use Eboni, the
following assumes you are too.

For glossy papers the K and LK are not used. Instead two curves are
made one warm and one cool. A neutral hue is achieved by blending the
2 curves. The warm curve uses the C and LC as grey inks and a little
bit of M is used in the deep shadows to improve dmax. For the cool
curve the M and LM are the grey inks and a little bit of C is used in
the deep shadows. In these cases the C (or M) is effectively the
"black" ink and LC (or LM) is the light black. Thus you need to tell
QTR the density of the LC (or LM)relative to C (or M).

For matte papers the K is used as well but the LK is not. So the warm
grey curve is formed by K, C and LC and the cool grey curve is formed
by the K, M and LM.In this case you effectively have 3 black inks so
QTR needs to know the density of C and LC relative to K (or M and LM
relative to K).

The LK is normally only used when printing with the Epson driver a la
EZBW mode. If you print only with a RIP you could use the LK position
for something else.

Hope this helps. 

Tom Moore 

--- In QuadtoneRIP@yahoogroups.com, "stasunas" <Astasunas@...> wrote:
>
> I am confused about creating an ink setup for my Epson 2200 printer 
> using MIS UT7 inks for Condor BriteWhite paper.
> In the User Guide I have determined my ink limit to be 85%, set my 
> slider to that and reprinter the calibration page and found Lt gray 
> to be 24% of Black.
> 

...

> 
> Frustrated in Florida,
> 
> Tony
>