QTR-Quadtone RIP

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