Hi Roger,
>... can you shed any light onto how you generate the
>point list which use to create the curves?
>It's quite precise.
>Is the goal of the curve to get the ink tone and
>smoothness right and then to correct the ramp by
>linearizing it?
I probably overkill on the points, but I like to get a curve that both hits
the tones I want and is quite linear, before I linearize. I've generally
found that the better the curve going into linearization, the better the
final curve. The Premier Art 325 curve hardly needs any linearization. The
Peregrine curve is rather rough, but I ran out of time and just wanted to
get something out there.
I also add points to smooth transitions. I don't entirely trust what the
smoothing algorithms can do to a curve. So, I avoid sharp turns by, in
effect, doing a bit of averaging myself. It's easy and seems to result in
better final curves.
One major advantage to QTR is that decimals are allowed in its 0 - 100
scale. In effect, one appears to have the full 16 bit scale available. So,
very fine adjustments can be made. How much all this is really needed is
debatable, but with Photoshop curves I found the 0 - 100 scale was a problem
and the full 256 scale actually made a difference.
The curves start as just rough guesses as to what the shape should be. I
put in some points and check the Curve Preview. This curve does not show
the results of the smoothing algorithms. So it's not exact, but it's very
useful and fast.
If I need to add an intermediate point, I copy points, paste into Notepad,
and add the points there, copying the results back to QTR's Points List.
When I read a test strip with the Print Fix Pro Spectro, I open the exported
text file in Excel and graph it (Insert>Chart>Line). For the tones, I've
standardized on plus and minus 5 units. So to get there I right click on
the vertical axis and format the scale.
For the Lab L graph, I just draw a straight line from the top to bottom
points. That tells me what points need to have more or less ink. For the
Lab B, I just compare what I have to the target, which in this case was PA
205-Scrapbook. Lab A can just be ignored. It's good with all papers and
carbon combinations I've used.
Note that about all I do for QTR profiling on these curves is set the
Default Ink Limit/dmax by just printing a 21-step file at 100 limit and a
straight line (0, 0) to (100, 100) curve. No further density or limits
need to be determined -- leave all blank. No calibration page at all needs
to be printed, just the 21-step. Once the dmax-default limit is set, I go
straight to the curves, using the Point Lists option. The curves will be
about the same for all matte papers, so just work from one that is already
done. (Be sure to clear the linearization tab numbers.) It might be easier
to delete many of the points at first to simplify things.
Obviously the warmer the target curve, the smoother the K2 print will be due
to more LK relative to Eboni. Additionally, the cooler the paper in the K2
printer, the smoother the print will be, again because more LK can be used.
I have not tried a really cold paper like Premier Art's Matte BW or Red
River Polar, but they might be interesting.
With the LK as the only ink at first, the top highlights are actually rather
smooth. The midtone grain is where some roughness can be seen, and whether
that is bothersome is a matter of how large the print is and one's
subjective views. I can see the grain with reading glasses at the normal
14" viewing distance, but not at much further out. I doubt I'll find it
objectionable in any large prints. If I do, I'll just have to fall back to
one of the other B&W printing options for that particular print. One reason
for the graphs of Lab A & B is so that people with any B&W inkset can print
larger versions that match the R1800 prints.
The Peregrine makes the smoother prints due to its cooler midtones and more
even tonal distribution. It's marginal on the dmax -- low 160's v. PA 325's
high 1.60's (1.7 on a good day with some printers). Whether the 0.05
difference really makes any difference may depend on the image.
The 9600s should be as good as my 2200. Both have 2880x1440 resolution and
4 pl dots. Assuming this is the case, I'll probably be selling my 7500 and
farm out my large display printing. I think I'm over color inks -- time to
spend more time doing B&W photography.
I hope this gives some guidance.
Paul
www.PaulRoark.com
______________________________
--- In DigitalBlackandWhiteThePrint@yahoogroups.com, "Paul Roark"
<paul.roark@...> wrote:
>
> The primary downside, from my perspective, of the R1800 100%
carbon workflow
> I'm now using (see http://www.paulroark.com/BW-Info/R1800.pdf) is
that the
> R1800 is limited to 13" wide paper, whereas I often make larger
prints - 16
> x 20 inches and above. There is no large format printer that uses
the small
> 1.5 picoliter drops of the R1800. However, using the 2200 as a
test bed,
> I've made some profiles that appear to make good, 100% carbon
large prints
> with K2 printers with MIS LK and Eboni in the usual K2 UC
positions. See
> http://www.paulroark.com/BW-Info/K2-Eboni-LK.pdf I think this
will allow
> those using the R1800 3-MK 100% carbon workflow to outsource their
larger
> prints to those who have larger K2 printers and use MIS LK and
Eboni MK.
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> Paul
>
> www.PaulRoark.com <http://www.paulroark.com/>
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