Re: Building PS curves for alternative processes with the Inkjet Companion

When I build my curves I only look at how the curve output values affect the
density readings of the final print.

For example - building a kallitype curve you may want to begin with a few
test curves like this:

Curve a:
Input Output
0 0
5 1
10 2
20 4
30 7
40 10
50 14
60 20
70 30
80 40
90 70
95 85
100 100

Curve b:
Input Output
0 0
5 2
10 3
20 5
30 8
40 11
50 16
60 23
70 34
80 50
90 75
95 91
100 100

Curve c:
Input Output
0 0
5 3
10 6
20 8
30 9
40 12
50 15
60 18
70 26
80 38
90 80
95 95
100 100

What's important here is that you have a good sampling across the range of
all the output values. The output values from 1 - 12 are especially
critical for nailing down the correct highlight values on your kallitypes.
Now print out your curves onto step tabs and make a fully toned print and
then measure the density of each block. Assemble the results by mixing and
matching the input/output values and then assemble about three more 'rough'
final curves and test them to come up with a 'final' curve. For example,
you may have found from your test curve that the 10%/2% input/output data
point made a 5% grey density reading on the print. So your final curve will
be 5%/2% input/output.

It's also important to remember that with alt-photo the curve is but one
variable in the whole operation. Things such as the sensitizer ratio and
coating thickness, paper variances, your exposure process, etc. all have a
potent effect on the outcome. Don't get too wrapped up in trying to get a
'perfect' curve unless you have a rigid control on all of the other
variables in the process first.

Hope it helps.

Regards,

Michael Klemmer

----- Original Message -----
From: "Silver Plated" <dstevenbryant@mindspring.com>
To: <alt-photo-process-l@sask.usask.ca>
Sent: Thursday, May 27, 2004 11:26 AM
Subject: Building PS curves for alternative processes with the Inkjet
Companion

> Good Afternoon Everyone,
>
> Recently I purchased an Epson 2200 (an a 1280) and this past weekend I had
an opportunity to make a digital inkjet negative to try printing as a toned
kallitype print. Before I go in to the particulars of my results and
questions let me point out that to make the negative I used Dan Burkholder's
Inkjet Companion Template, using his curve for palladium prints.
Additionally my monitor is calibrated and profiled and I'm using Pictorico
OHP for the inkjet negative substrate. I choose the kallitype process since
it is relatively inexpensive.
>
> I knew that using Dan's curve would most likely require adjustments to
produce a good result, in fact I hoped that the print would need adjustment
to provide myself with the opportunity to learn how to make adjustments to
curves for various processes. The final print was extremely flat. There was
very little differentiation in most of the steps in the included step wedge
on the print. This is in contrast to the quad tone print I made as a proof.
>
> The 0% step read about .09 and the 100% step read about 1.35 on my
densitometer. Most of the mid-tone steps had a reading of about .25 to .35
(I'm working from memory here). Additionally I have not established the
minimum print time for black but I assume I'm pretty close since the 100%
step was 1.35. I plan on establishing the minimum black time this weekend
with a blank piece of OHP.
>
> My question today is; is there a way to correlate my densitometric
readings that will result in the desired changes in the PS curve to produce
good separation. Also how much difference in log density values should one
expect to see in the step wedge mid-tones? Also if I read the transmissive
values on the negative are there aim points for the differences from step to
step that one should observe?
>
> Hopefully my questions seem rational and clear, if not, someone, anyone
please correct me!
>
> Also as time permits I plan to test Keith Schriber's colorization values
and curves along with several other curves different individuals have sent
me.
>
> Thanks,
>
> Don Bryant
>
Received on Sat May 29 10:52:18 2004