Hi Roy,
After playing with the curve creation tools on a Mac with an Eye-One
Pro, I have
the following observations/questions. I wish I can get some kind
insightful
answers/comments from you?
All the efforts has been for the Hahnemuhle Photo Rag 308 paper on a new
Epson
3800 with the Ultrachrome K3 inks (Matte Black, of course).
1. Using the Epson's Advanced Black and White (ABW) mode (1440dpi,
"Normal",
warm toned a little bit), the linearity was not good (compressed
highlights
and shadows, expecially the shadows). However, the D-Max was 1.624:
File: /Users/leping/Desktop/3800
Linearization/ABW-RL_1440_Normal-out.txt
Step Dens Lab A B
0.00 0.040 96.47 0.40 0.35 - |b
L +
5.00 0.077 93.34 0.58 0.53 - | b
L +
10.00 0.132 88.79 0.68 0.81 - | ab
L +
15.00 0.198 83.61 0.91 1.03 - | ab
L +
20.00 0.260 79.05 0.96 1.37 - | a b
L +
25.00 0.320 74.76 0.96 1.54 - | a b
L +
30.00 0.391 69.91 1.17 1.19 - | b L
+
35.00 0.464 65.26 0.78 1.87 - | a b L
+
40.00 0.542 60.50 0.85 2.14 - | a L b
+
45.00 0.618 56.19 0.94 2.32 - | a b
+
50.00 0.704 51.57 0.80 2.49 - L a b
+
55.00 0.800 46.76 0.81 2.06 - L | a b
+
60.00 0.895 42.38 0.74 1.86 - L | a b
+
65.00 1.024 36.87 1.03 1.72 - L | a b
+
70.00 1.133 32.61 0.93 1.51 - L | a b
+
75.00 1.257 28.20 0.77 1.39 - L | a b
+
80.00 1.370 24.54 0.47 0.90 - L |a b
+
85.00 1.475 21.40 0.12 1.10 - L a b
+
90.00 1.550 19.30 0.17 1.15 - L a b
+
95.00 1.602 17.93 0.43 1.25 - L |a b
+
100.00 1.624 17.34 0.59 1.61 - L | a b
+
2. With a blend (created by Richard Lohman to match his excellent
Hextone prints off a modified Epson 3000) of your released 3800
curves for the paper (to achieve a similar warmth, a split of
the cool, neutral, and the sepis curves), the linearity was good,
but the D-Max was only 1.552:
QTR-Linearize-Data version 2.5.1.0
File: /Users/leping/Desktop/3800 Linearization/QTR-1440-RL_Split-out.txt
Step Dens Lab A B
0.00 0.037 96.69 0.41 0.35 - |b
L +
5.00 0.086 92.62 0.61 0.34 - |ba
L +
10.00 0.134 88.72 0.79 0.36 - |b a
L +
15.00 0.184 84.73 0.95 0.41 - |b a
L +
20.00 0.237 80.69 1.09 0.42 - |b a
L +
25.00 0.290 76.85 1.26 0.47 - |b a
L +
30.00 0.356 72.28 1.49 0.60 - | b a
L +
35.00 0.414 68.41 1.49 0.67 - | b a L
+
40.00 0.478 64.35 1.65 0.83 - | b a L
+
45.00 0.542 60.53 1.71 1.01 - | b a
+
50.00 0.619 56.11 1.73 1.11 - | Lb a
+
55.00 0.697 51.91 1.98 1.28 - |L b a
+
60.00 0.771 48.18 1.80 1.58 - L | ba
+
65.00 0.863 43.84 1.51 1.72 - L | b
+
70.00 0.943 40.27 1.67 1.64 - L | b
+
75.00 1.036 36.36 1.91 1.92 - L | b
+
80.00 1.135 32.53 2.11 2.15 - L | b
+
85.00 1.267 27.86 2.22 2.28 - L | ab
+
90.00 1.360 24.86 2.10 2.33 - L | ab
+
95.00 1.451 22.09 1.88 2.06 - L | ab
+
100.00 1.552 19.24 1.50 1.86 - L | ab
+
3. Next, I did the ink limit and separation tests, using both
your "inkseparation.psd" pattern as we as Daniel (dchow1961)'s
modified Ink_Limit_Pattern_Page from the list's Files/Tools
section. The measurements were done both visually and with
the Eye-One Pro.
What I found is, for all the 3800 inks, more ink always produces
higher densities, although the shoulder location can be clearly
identified. The following is an example of the 3800 K (Matte
Black):
QTR-Linearize-Data version 2.5.1.0
File: /Users/leping/Desktop/3800 Linearization/K-InkLimit-out.txt
Step Dens Lab A B
0.00 0.043 96.21 0.51 0.66 - | b
L +
5.00 0.413 68.48 1.22 2.91 - | a b
+
10.00 0.700 51.79 1.60 4.08 - |L a
b +
15.00 0.854 44.23 1.61 4.11 - L | a
b +
20.00 1.027 36.75 1.52 3.82 - L | a
b +
25.00 1.205 30.02 1.33 3.23 - L | a b
+
30.00 1.273 27.67 1.16 2.59 - L | a b
+
35.00 1.372 24.48 1.06 2.39 - L | a b
+
40.00 1.445 22.26 0.94 2.17 - L | a b
+
45.00 1.514 20.28 0.89 2.17 - L | a b
+
50.00 1.556 19.13 0.82 2.06 - L | a b
+
55.00 1.579 18.53 0.77 1.81 - L | a b
+
60.00 1.599 18.01 0.76 1.83 - L | a b
+
65.00 1.609 17.73 0.65 1.75 - L | a b
+
70.00 1.610 17.70 0.69 1.85 - L | a b
+
75.00 1.623 17.39 0.65 1.77 - L | a b
+
80.00 1.624 17.36 0.67 1.88 - L | a b
+
85.00 1.624 17.34 0.61 1.87 - L | a b
+
90.00 1.625 17.33 0.64 1.80 - L | a b
+
95.00 1.630 17.20 0.63 1.95 - L | a b
+
100.00 1.630 17.19 0.64 1.79 - L | a b
+
so that, as the ABW driver results showed, the Ultrachrome K3
Matte Black ink is able to produce a D-Max of 1.63.
And I found, visually the ink limits are:
K: 60 / C: 85 / M: 85 / Y: 60 / LC: 90 / LM: 90 / LB: 80 / LLB: 85
If this is true, then my first question is, is the ink limit
settings (45/50) in your released 3800 Photo Rag curves too
low, contributing to the reduced D-Max using these curves?
I went to check your released Photo Rag curve ink limit
numbers for the 4800/7800/9800 UC inks, and can see the
limits were all 100. If the 3800 shares the same K3 ink
with its bigger brothers, why the settings should be so
different?
And, since the lowest L values achieved with the curve
settings can be seen from the linearization array (the last
number on the line), after converting to density, we can
see with the 100% ink limits you were able to attain
D-Max of 1.70 (Coolse) / 1.69 (Cool and Sepia) / 1.65 (Warm)
with your 4800 curves!
Nevertheless, I noticed the Coolse and Cool curve description
file headers are different from the other two, with the
comment line that read "for 4800 with ultrachrome k3 inks
and MIS Eboni in the K slot". This is quite confusing, but
since I tend to think the MIS Eboni Black ink would produce
D-Max values deeper than 1.70 (Richard got 1.76), and you
released the curves as a family in the folder named for
UC ink the comment is just a leftover from other calibrations?
Then, without changing the ink limits, I tried to increase the
BOOST_K value from 55/60 to 85. The results showed immediately
an increased D-Max of 1.598.
This encouraged me to create a new set of 3800 curves from
copying yours and changing the default ink limits to 55 and
the BOOST_K to 100. I could have tried something like a
15% GRAY_OVERLAP as well but decided to do one thing a time.
I always let prints to dry for at least 10 hours before any
measurement. I had no problems with linearization at all,
and the post-linearization results, from the altered 55/100
settings, and still with the Richard's curve spliting formula,
the result was:
File: /Users/leping/Desktop/3800
Linearization/Boost100-Linearized-RL-Split-out.txt
Step Dens Lab A B
0.00 0.051 95.57 0.40 0.37 - |b
L +
5.00 0.095 91.81 0.63 0.35 - |ba
L +
10.00 0.145 87.83 0.82 0.38 - |b a
L +
15.00 0.192 84.08 1.03 0.40 - |b a
L +
20.00 0.248 79.86 1.19 0.43 - |b a
L +
25.00 0.297 76.39 1.39 0.48 - |b a
L +
30.00 0.348 72.81 1.65 0.59 - | b a
L +
35.00 0.414 68.39 1.67 0.78 - | b a L
+
40.00 0.472 64.72 1.83 1.00 - | b aL
+
45.00 0.534 61.02 1.96 1.19 - | b La
+
50.00 0.605 56.88 2.04 1.33 - | Lb a
+
55.00 0.674 53.17 2.35 1.55 - |L b a
+
60.00 0.751 49.17 2.21 1.83 - L| ba
+
65.00 0.842 44.80 1.96 2.17 - L | ab
+
70.00 0.916 41.43 2.10 2.18 - L | b
+
75.00 1.017 37.13 2.17 2.45 - L | ab
+
80.00 1.114 33.34 2.27 2.67 - L | ab
+
85.00 1.221 29.45 2.25 2.76 - L | a b
+
90.00 1.319 26.16 2.14 2.68 - L | a b
+
95.00 1.434 22.58 1.73 2.30 - L | a b
+
100.00 1.587 18.32 0.93 2.22 - L | a b
+
so the D-Max increased to 1.587 from the 1.552 with the
released curves, but still lower than the possible value of
1.63 from the ink limit calibration.
Thus, my next question is, should I try to make the default
ink limit to 100%, and put in a little GRAY_OVERLAP next, in
the hope to further increase the D-Max on the Photo Rag?
4. The last questing is the most puzzling. From my ink limit
calibration, the (minimum) L values at 100% ink ware 17.19 (K),
30.17 (LK), and 17.19 (LLK). After interpolation (directly, or
using kevbell007's GRAY_VAL_Interpolation_for_3_inks spreadsheet,
also in the group's Files/Tool folder), the relative density of
the 3800 UC inks should be [100/24.9/7.0].
However, in all your released 3800/2400 curves, such ratios has
been [100/33/12], which is way off my measurements. Then I went
to your 4800 curves and found the ratios there were 100/24/9,
that is much closer to my numbers.
What happens if I use the [100/25/7] results to create new curves?
I have to say I did try to fool the QTR software to install the
4800 curved for the QTR3800 printer (by changing the folder name),
but the results were very bad with heavy color casts so the
direct substitution is not a solution.
Thank you so much for your patients (and all who is following me
this far) reading this long post.
Yours very truly,
Leping
San Mateo, California
www.lepingzha.com <http://www.lepingzha.com>
[Non-text portions of this message have been removed]Message
Questions to Roy: 3800 UC Curves for Photo Rag 308 (long)
2007-04-26 by Leping Zha