QTR-Quadtone RIP

Here is my understanding -

Whenever you are putting down ink onto paper, lighter shades require less  
ink. As you increase the amount of ink to get darker shades, you get to a  
point where more of the same ink fails to produce a darker tone. In fact,  
depending on the particular ink and paper combination, you can get to the  
point where adding more ink actually causes the tone to appear lighter.  
That is where the ink limit comes in. You want to set the ink limit so  
that the printer will never apply more ink than the level that produces  
the darkest shade possible for that ink/paper combo.

Ink density is the relative density of a particular ink to the darkest ink  
of the ink set. This setting is used by the driver software to know when  
to switch to the next lighter shade of ink instead of just reducing the  
amount of the darker ink being applied. The darkest ink is always 100 and  
the lighter inks have values less than 100. During curve creation you  
evaluate the relative densities and enter a value that represents where,  
as a percentage, the darkest level of the lighter ink lies on the curve of  
darkest ink.

This is over simplified but say if you only had two inks, the darkest  
level for the lighter ink would only get as dark and the 50% (or there  
abouts) level of the darkest ink. Then the software would start to use a  
combination of the two inks at say, 70%, and gradually reduce the amount  
of darkest ink use and increase the lighter ink use until maybe 30%, where  
it would stop using any of the darkest ink and then it would just be using  
lesser amounts of the lighter ink until you got to 0.

It gets more complicated with more inks, such as with Cone's K7 inks, but  
the principles remain the same. The whole idea is to make the transitions  
between the various ink shades as smooth as possible so that you get an  
even range of tones in the final print.

Hope this helps,
Steve

    On Mon, 13 Aug 2007 08:14:52 -0700, David <dkfreed@...> wrote:

> I've posted this question before, but didn't really understand the
> answers. So again, can someone help me understand what the ink density
> and ink limit settings do? How are they different, the same?  Can
> someone give an example of what changing these settings do?
>
> I have only a layperson's understanding, so looking for help.
>
> Best, David.
>
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