QTR-Quadtone RIP

Hi Tyler,

I think the answer to your question is yes, but ...

Having experimented over the last few months with HP-C6 aiming for neutral
and needing to warm it up in the 3/4 tones to achieve that, I got very
frustrated with the inflexibility of QTR to re-linearise after editing a
toning curve.

The problem is that you can add a toner as you describe below, but when you
linearise the tone curve will change and you can't edit it further, you can
only start again with a new tone curve. There is no way, I can see, to do
sequential linearizations in QTR and that's a real pain.

My solution was to write my own linearization program that takes a set of
QTR curves (actual ink values in Quad file) and linerarizes them. This let's
me edit a toner curve ink values (often manually in Excel) and relinearize
them again. It even allows me to look at the predicted re-linearized ab
curves before I print them and decide if I need to tweak them further.

Through testing this HP-C6 approach I also discovered that the QTR curve
model that doesn't use many overlapping inks, is suspectable to
posterization. I had a print that posterized and someone suggested is was
possibly a problem with QTR curve model.
So I created another curve model that was more like Cone's model where the
inks overlap much more and indeed the posterization problem was solved. BUT
the cost of this overlapping ink approach is reduced dmax. On Canon Rag 310
the dmax drops from L=15.3 to L=16 due to the other inks polluting the
darkest ink. So you've got to choose between the limitations of the two
approaches.

Learn't a lot about QTR in the last few months.

Mike




On 5 March 2010 23:06, tboleyyh <tyler@...> wrote:

>
>
> after going through all the references I can find, it looks to me like the
> Photoshop curve import function in the Windows version with curve creation
> is the most straightforward, current, and viable approach to making unique
> toner setups..
> Would you QTR experts here agree?
> Thanks,
> Tyler
>
>  
>


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