QTR-Quadtone RIP

Hi Colin,

I'd recommend you try the existing profile with just the ink positions
changed and see if it works for you.

>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;

It's probably unfortunate that my profiles use the 70 ink limit.  That was a
bit arbitrary and based on the very high loads I found I needed for some
un-coated papers to hit their dmax.  Note that the real action is setting
the end points in the curve creator -- at 38 for HPR.  So, 3 channels at 38
X 0.7 for an actual 26.6 per channel is an effective total ink limit of
79.8.

Note that the Dmax test is just for setting this end point for each curve.
It uses straight line curves that do not make for a good final curve at all.

After the dmax is determined, go to the 3MK-Start profile to print the test
strip for linearization -- after you've set the end points of the curves.
The Notes tab in that profile also has the instructions.  

All the profiles use about the same curves.  The ends are the only places
where things vary a bit due to different end points and the need to have a
smooth curve leading up to that point.  With the Windows Curve Creator and
its curve preview this is easy to do.  I'm not sure what the Mac situation
is.  If you don't have a preview, it's going to be hard to make good curves
from scratch.  Again, I'd just use the HPR curves I made.  Even if you're
dmax point is slightly different, it's probably close enough that only a
minor adjustment of the very end point will be needed.

I'm not sure where your 67% is coming from.

> 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 ...

Again, I'd try the existing profile with just the ink positions changed
first. I can't tell what has gone wrong with your efforts.

>...

>... I was surprised to attain Dmax figures of 
>1.76. Can such a figure be obtained in practice.

Yes.  

(By the way, this system can also make the best Arches Hot Press (uncoated
watercolor paper) image I've seen with an inkjet, attaining up to a 1.6 dmax
with at paper -- rather high for an un-coated paper.)

Paul
www.PaulRoark.com