QTR-Quadtone RIP

rossfmj <ross.jarvis@...> wrote:

> **
>
>
> Paul
>
> After the initial calibration and second calibration prints, I am getting
> a Dmax of 1.60 from the Black at 25% default ink limit.,
>
That is low for H. Photo Rag.  Is that what your full Calibration Print at
100% showed as the darkest?  I just looked at an old 1400 H. Photo Rag QTR
profile that used Eboni MK, and the ink limit was 30 with a boost to 40.
 This produced a dmax of 1.71.


both C and M came in at 57% of that with Density of 1.25 (both are the
> same).
>
That sounds like it should be within range.  However, if you are getting
posterization or too low a slope in the gray ramp near the 100%, you might
want to lower the C and M ink limits.  A dark gray at 30 density is what I
see in the old (not UT14) profile I'm looking at.


In looking at your linearization numbers, it seems like the 95% to 100%
pre-linearization gap is more than I'd expect.  The 90 to 95% gap is too
small.  I wonder if your C curve was going flat there.  You might be able
to correct this by backing off on its ink limit.  Set the midtone ink
limits were the inks still have a good positive slope to them.



LC was 46% of C meaning 26% in the ink descriptor (at Density .80), if I've
> got this right and LM was 48% of M being 27% in the descriptor (Density
> .85).
>
It's OK only if it works!


> Do the C and M percentages seem high?
>

Not necessarily, but if the slopes are too flat by then, it could be a
problem.



> I'm really not sure how to set the Black Boost, when or why, or what
> numbers to use.
>

See the above comment.

Paul
www.PaulRoark.com




>
> The cool descriptor including linearisation is;
>
> # Ink positions:
> # Black: Ebony black
> # Magenta: Warm photo black
> # Light Magenta: Dilute warm photo black
> # Cyan: Cool photo black
> # Light Cyan: Dilute cool photo black
> # Yellow: Gloss optimizer ("GLOP")
>
> GRAPH_CURVE=YES
> N_OF_INKS=6
> DEFAULT_INK_LIMIT=25
> BOOST_K=
> LIMIT_K=
> LIMIT_C=
> LIMIT_M=
> LIMIT_Y=
> LIMIT_LC=
> LIMIT_LM=
>
> N_OF_GRAY_PARTS=3
> GRAY_INK_1=K
> GRAY_VAL_1=100
> GRAY_INK_2=C
> GRAY_VAL_2=57
> GRAY_INK_3=LC
> GRAY_VAL_3=26
>
> GRAY_HIGHLIGHT=10
> GRAY_SHADOW=10
> GRAY_OVERLAP=
> GRAY_GAMMA=1
> GRAY_CURVE=
>
> N_OF_TONER_PARTS=0
> N_OF_TONER_2_PARTS=0
>
> N_OF_UNUSED=3
> UNUSED_INK_2=M
> UNUSED_INK_3=LM
> UNUSED_INK_4=Y
>
> LINEARIZE="0.01 0.04 0.09 0.14 0.19 0.25 0.30 0.35 0.43 0.53 0.62 0.71
> 0.79 0.86 0.92 0.98 1.10 1.23 1.33 1.39 1.60"
>
> thanks
>
> Ross
>
> --- In QuadtoneRIP@yahoogroups.com, Paul Roark wrote:
> >
> > If you are using QTR, be sure the C or M ink limit is set low enough that
> > it's maximum density at its ink limit is well below the dmax of the MK.
> > You might also want to use the Black Boost for the last 10% of the MK ink
> > curve. When you use the Boost, the second calibration print is done at
> the
> > K ink limit, not the Boost setting.
> >
> > Paul
> > www.PaulRoark.com
>
>  
>


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