QTR-Quadtone RIP

I am having some difficulty setting up a new profile.

I print the ink limit page to characterise the inks. I then print the ink separation page with the limit slider set to where the ink saturates the page, in this case 85%. I look at the figures and measure and set the crossover points. I use the GUI to fill the figures into the curve creation page.
Then I print the 21 step wedge, that prints ok, but the densities at the 70%-100% end are all cramped up with very little difference between them. I use Photoshop and the step wedge script to read the 21 step values. I copy and paste these L* values into the linearization boxes in the GUI.
At this point the procedure fails with a message saying that the steps are not in order. They are in order but there is very little difference between the steps at the black end. I think the closeness of the steps is the problem.

Is there a method to reduce the densities at the black end. Highlight, shadow, gamma, etc so I can linearise the curve?

Cheers
Greg Nixon

It sounds like  you've set the ink limit too high.

First, be sure that the ink limit is (at most) set to what I call the left
edge of the plateau.  As the K density rises, it wii hit a plateau where it
will see-saw for a while.  You want to stay off that plateau.

Second, you might try setting the ink limit to the last K step where you
actually can visually see a density increase.  Then have the black boost
carry the K to a higher point if your scanner or spectro measures a deeper
black beyond that point.

I would concentrate on getting these initial settings correct and not alter
the defaults in the middle tabs.

Paul
www.PaulRoark.com

On Thu, May 2, 2013 at 6:44 AM, Greg <gregnixon@...> wrote:

> **
>
>
> I am having some difficulty setting up a new profile.
>
> I print the ink limit page to characterise the inks. I then print the ink
> separation page with the limit slider set to where the ink saturates the
> page, in this case 85%. I look at the figures and measure and set the
> crossover points. I use the GUI to fill the figures into the curve creation
> page.
> Then I print the 21 step wedge, that prints ok, but the densities at the
> 70%-100% end are all cramped up with very little difference between them. I
> use Photoshop and the step wedge script to read the 21 step values. I copy
> and paste these L* values into the linearization boxes in the GUI.
> At this point the procedure fails with a message saying that the steps are
> not in order. They are in order but there is very little difference between
> the steps at the black end. I think the closeness of the steps is the
> problem.
>
> Is there a method to reduce the densities at the black end. Highlight,
> shadow, gamma, etc so I can linearise the curve?
>
> Cheers
> Greg Nixon
>
>  
>


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

Hi Paul, thanks for your reply.
I lowered the ink limits and set the gamma to 2.2 which drops the black curve off more sharply.
The 21 step wedge is now much better at the dark end.
When you look at the ink density pattern, do you check by eye to see where the density flattens out or actually measure it. The second saturation scan is done at 85%, where is this taken into account in the curve creation?

I have done this before but I accidently overwrote the values with blank data. I can't remember what I used for a reference grey card in the linearisation process. I have a couple of IT8 targets. Is the grey scale at the bottom of that card suitable?

Cheers
Greg Nixon



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

>
> It sounds like  you've set the ink limit too high.
> 
> First, be sure that the ink limit is (at most) set to what I call the left
> edge of the plateau.  As the K density rises, it wii hit a plateau where it
> will see-saw for a while.  You want to stay off that plateau.
> 
> Second, you might try setting the ink limit to the last K step where you
> actually can visually see a density increase.  Then have the black boost
> carry the K to a higher point if your scanner or spectro measures a deeper
> black beyond that point.
> 
> I would concentrate on getting these initial settings correct and not alter
> the defaults in the middle tabs.
> 
> Paul
> www.PaulRoark.com
> 
> On Thu, May 2, 2013 at 6:44 AM, Greg <gregnixon@...> wrote:
>