QTR-Quadtone RIP

Greg <gregnixon@...> wrote:

> **
>
>
> I am attempting to create a profile with my 1400 using UTFS inks.
>
My memory of this setup is that the M and C are the same density, and the LC
and LM may be the same or very close.  Keep in mind that, in the QTR
partitioning, the inks in a progression must be different densities.  So,
you'll have to have the grays be, for example, Y, LC, C, K, and then set up
a toner channel with, for example, Y, LM, M, K (I'm forgetting if the K
needs to be there).

Is this matte paper with K = Eboni?

At any rate, first try Y, LC, C and K.  have the others not used.

If you are using PK and have it in the K position, recall that the C and M
might have a dmax that is greater than the PK, but they'll do that with huge
loads that will probably result in pizza wheel marks.  So part of what you
need to do is reduce the ink loads of the lighter inks below their dmax
points.

>
> Looking at a printed 21 step wedge, the lighter end seems to rise smoothly
> to about 60% where it flattens out, and from there on there is not much
> difference between the darker steps.
>

What profile where you using?  Was this the pre-linarized QTR output from an
initial profile?

As long as the differences in the 21-step print are enough that the results
will linearize with QTR, this might not matter.  You're often better off
with compression of the dark end than not because this gives the program
real data to use as opposed to interpolation.

>
> The prints look as you would expect, not too bad until the part-shadow and
> shadow.
>
> I have an idea that the dark grey ink is being set as lighter than it
> really is.
> When I print the first calibration print, the K ink limit comes up at 45%
>

If the K is fairly flat between 35 and 45, consider putting the ink limit at
35 and the boost to 45.

Consider using 35 as the ink limit for the M and C -- in fact for all inks.
 Use less light ink.  It's expensive water and the 1400's 1.5 pl drops don't
need it.  Particularly with glossy papers & inks, the higher the load, and
wetter the paper, the more problems with pizza wheel marks.

... in the calibration scan, the 100% patch of the K row is the same density
> right down to 45%.
>
That is rather normal.  You want to set the final K ink load at the left
edge of the plateau.  But, again, I prefer to use boost for the final 10%
because that area usually has a very low slope.

That means that I am attempting to find the 100% LK point down below 45% of
> K. I think it is actually higher than that.
>
There is no LK in that inkset.  But, again, see what the density of the
lighter inks are at 35% and consider that as the default ink limit.

Later when the toner channel is set up, split the ink limit between the gray
and toner channels.

I hope this helps.

Paul
www.PaulRoark.com




>
> Any comments?
>
>  
>


[Non-text portions of this message have been removed]