QTR-Quadtone RIP

I'm having difficulty achieving the Dmax that I think the following ink/paper combination 
should be able to achieve:

7800, K3, Innova PSC.

When printing the ink separation page, the K values where as follows

65.00	17.93
70.00	17.89
75.00	17.41
80.00	17.15
85.00	17.20
90.00	17.59
95.00	17.36
100.00	17.53

Therefore, I have set the K ink limit to 75 and black boost to 80.  No matter what I try, I 
can't get anything close to 17.15 when printing the 51 step random target with the non-
linearized curve I have created.  I'm also getting reversals on the 100%K patch.  The 
following is the end of the data produced by QTR-Linearize-Data.app.  

90.00	1.589	18.26	0.82	2.00	-         L                   |  a    b                     +
92.00	1.596	18.07	0.81	2.13	-         L                   |  a    b                     +
94.00	1.599	18.01	0.79	2.17	-         L                   |  a    b                     +
96.00	1.603	17.89	0.84	2.13	-         L                   |  a    b                     +
98.00	1.605	17.83	0.76	2.40	-         L                   |  a     b                    +
100.00	1.594	18.13	0.71	2.50	-         L                   | a       b                   +

Even the 98.00 patch is at 17.83 - a far cry from 17.15 . . . or am I being too picky?  It 
seems that with the K ink limit of 75 and boost of 80, that the 100 patch generated with 
the curve should be the same as the 80 patch on the ink separation page, or am I missing 
something? 

Thanks for any insight you can provide.

Best.

Josh

Josh,

You might be a tad picky, but only a tad. Notice that the ink 
separation page prints in 5% steps, yet you are linearizing in 2%. 
Nothing wrong in that per-se, but you are more likely to find 
anomalies.

The true pure K limit may be somewhere between 75 and 80%. QTR 
proabaly lays down some LK ink down to 98% patch and that may be 
interacting with the maximum K the paper is capable of handling.

So I would set the K limit to 75%, and leave the K boost empty. Or 
else, K limit=70, K Boost=75. If this solves the 98-100 reversal, 
you should be good to go. To eke out the last ounce of Dmax may 
require some interations. I personally don't get too bothered by 
1.65 versus 1.62 densities.

Tell us how it goes.

Shilesh

--- In QuadtoneRIP@yahoogroups.com, "joshhackney" <joshhackney@g...> 
wrote:
>
> I'm having difficulty achieving the Dmax that I think the 
following ink/paper combination 
> should be able to achieve:
> 
> 7800, K3, Innova PSC.
> 
> When printing the ink separation page, the K values where as 
follows
> 
> 65.00	17.93
> 70.00	17.89
> 75.00	17.41
> 80.00	17.15
> 85.00	17.20
> 90.00	17.59
> 95.00	17.36
> 100.00	17.53
> 
> Therefore, I have set the K ink limit to 75 and black boost to 
80.  No matter what I try, I 
> can't get anything close to 17.15 when printing the 51 step random 
target with the non-
> linearized curve I have created.  I'm also getting reversals on 
the 100%K patch.  The 
> following is the end of the data produced by QTR-Linearize-
Data.app.  
> 
> 90.00	1.589	18.26	0.82	2.00	-         
L                   |  a    b                     +
> 92.00	1.596	18.07	0.81	2.13	-         
L                   |  a    b                     +
> 94.00	1.599	18.01	0.79	2.17	-         
L                   |  a    b                     +
> 96.00	1.603	17.89	0.84	2.13	-         
L                   |  a    b                     +
> 98.00	1.605	17.83	0.76	2.40	-         
L                   |  a     b                    +
> 100.00	1.594	18.13	0.71	2.50	-         
L                   | a       b                   +
> 
> Even the 98.00 patch is at 17.83 - a far cry from 17.15 . . . or 
am I being too picky?  It 
> seems that with the K ink limit of 75 and boost of 80, that the 
100 patch generated with 
> the curve should be the same as the 80 patch on the ink separation 
page, or am I missing 

> something? 
> 
> Thanks for any insight you can provide.
> 
> Best.
> 
> Josh
>