QTR-Quadtone RIP

Thanks, Paul.

I think I understand what you are doing to set the black ink limit.  
Printing the 21 step grayscale with the straight line profile 
eliminates the need to print the initial calibration target at 100%.  
Do you pick the absolute blackest black as read with a spectro for 
your black Dmax or do you back off a little bit?

I assume that once you have established the black ink limit using 
this approach, you then print the calibration target (with 
calibration mode now turned on) at the above determined black ink 
limit and proceed with partitioning the other inks.

It also appears you are still trying to stick with QTR default 
settings for all settings on the Gray Curve and Toner Curve tabs.

Sorry for all the questions, but it does get a little complex with so 
many options and approaches.  I guess no matter how you get there, 
the key is to get smooth curves and transitions, no unwanted color 
crossovers or reversals, a linear tone scale, and the best Dmax 
possible (without getting into unstable territory).  Having built 
some pretty good profiles (with a LOT of iterations) I am looking for 
a simpler, faster, more effective way.    

Regards,
Lou

--- In QuadtoneRIP@yahoogroups.com, "Paul Roark" <paul.roark@...> 
wrote:
>
> Hi Lou
> 
> 
> >--- In QuadtoneRIP@yahoogroups.com, "Paul Roark" <paul.roark@> 
> wrote:
> 
> >> The MK is the highest load ink. So, I use it for the 
> >>default ink load.  Usually you can then simply ignore 
> >>the black boost and other ink limits. I
> >> set this with a single 21-step curve printed with a 
> >>straight line curve profile. I make the curve by 
> >>entering the coordinates (0, 0) and (100, 100)
> >> in QTR's "Point List." (Tools>Curve Creation>Curve>
> >>Point List tab) In short, on 21-step print takes 
> >>care of dmax and all ink limit (and black
> >> boost) issues in making the profile.
> 
> 
> >Now that I have found the Load Curve and Point List tabs,
> > can you elaborate a little... Do you use 
> >just those two points above?
> 
> Yes, those 2 end point define a straight line curve from (0, 0) to 
(100,
> 100). I set the ink load for the black ink at 100.  All other inks 
are
> turned off.  I then make a profile named, in effect, as a K 
straight line 0
> - 100.  Then, I print a 21-step file with that profile.  The x% 
label on the
> 21-step test print where the dmax is reached defines the default 
ink limit.
> 
> > And only for the black ink or for all inks.
> 
> I just print the black ink for the default in limit.
> 
> > I was under the impression that printing without any 
> >linearization data entered was the same as printing 
> >with 0,0 and 100,100. I guess that is incorrect?
> 
> There needs to be some underlying profile.  The linearization just 
makes an
> overlaying correction curve.  (Not that I know the details of the
> programming.  You'll need to ask Roy for that.)
> 
> >I have read the following description on your website and it 
> >appears similar in many respects, but I didn't see a reference 
> >to the above. 
> 
> >"QTR, 2200, 4K+, Matte BW, Carbon & general monotone inkset curve 
> >profiling"
> 
> Those were some preliminary experiments and notes.  I think as you 
gain
> experience you develop your own style as to how you do things.  I've
> increasingly tried to minimize the variables but at also directly 
describing
> the curves in the point lists.  As an example, for partitioning, the
> automatic system is a good start and most would stop there.  I, 
however, do
> a screen grab of it and turn the curve into point lists.  Then I 
directly
> manipulate that to get a fairly straight carbon core.  This allows 
for
> simpler toner curves.
> 
> > ... your approach does seem to elimiate 
> >significant iterations and give a better result, 
> 
> That's the goal.  I hope it's going in that direction.  I'm really 
not an
> expert in QTR, however.
> 
> > Is this only used for Quad inks, or can it also be 
> > used for a color inkset like the UC inks?
> 
> See what I've done with the R260 at
> http://www.paulroark.com/BW-Info/R260-Color.pdf  I'd love for QTR 
to be able
> to pass RGB information through it, but at this time it converts an 
RGB file
> into a GS file.  The color profiling I've been able to do just with
> neutralizing a 21-step is surprisingly good.  I just printed some 
color
> photos using this plus an increase in the saturation (which I do 
for most
> MIS color pigs to match the Epson colors) that are about the best 
color I've
> ever printed.  If QTR could do this, it would allow me/us much more
> flexibility to, for example, have an 1800 with CMY in it that we 
drive with
> QTR for color, and then have the remaining slots filled with more
> interesting B&W oriented inks. 
> 
> Paul
> www.PaulRoark.com
>