QTR-Quadtone RIP

--- In QuadtoneRIP@yahoogroups.com, "Paul Roark" <paul.roark@...> 
wrote:
>

> In the Curve Creator, I'd just copy the GL numbers and paste them 
into the Y
> points list.
> 
>> Hope this helps.
> 
> Paul
> www.PaulRoark.com
>
Thank you Paul for your response.

I have prepared QTR qidf files for HPR from your 3MK-Dmax-test 
through to re-linearizing using 67% and your 70% figure for the 
calculation of the end point; also I have copied the curves in the 
QIDF profile that you published for that paper.  In each case I do 
not get a linear curve but one that is like a gaussian curve but  
asymptotic toward the darker end, with the curve being too light.  
You should be able to generate the curve I get from using your HPR 
profile:


L	equal steps
95.43	95.43
92.31	91.67
89.29	87.91
86.04	84.14
82.87	80.38
79.73	76.62
76.93	72.86
74.26	69.09
72.07	65.33
69.67	61.57
67.26	57.81
64.93	54.04
61.81	50.28
57.67	46.52
53.06	42.76
47.61	38.99
41.88	35.23
35.50	31.47
29.85	27.71
26.08	23.94
20.18	20.18
 My spectrometer, the X-rite pulse elite measures L values, and 
these are in the first column.  The second equally divides the steps 
between Lmin and Lmax.  These can be plotted in a spreadsheet to 
illustrate the re-linearized curve.  Lmin of 20.18 is, I understand, 
equivalent to a Dmax of 1.65.

The mid point L value is 67.26 whereas, I presume it should be about 
57.8.

I have tried using the Ink Limit and Gamma sliders but cannot 
achieve a linear curve.  By adjusting the ink limits, the Dmax 
worsens.

Can you help me please?

Incidentally, I printed the 3MK-Dmax-test for Eboni in the MK, PK 
and Y slots separately, but at 100%, to check that my modifications 
were working correctly.  I was surprised to attain Dmax figures of 
1.76.  Can such a figure be obtained in practice.

Colin