Digital BW, The Print

Richard,

Thank you very much for your assistance. At present the main benefit 
is to learn to walk before I can run - as you say the learning curve 
seems pretty steep. I'll work along the lines of your instructions 
and see where it leads - at least I'm beginning to understand the 
relationship of the curves. 

My apologies in advance for when I get back to you:)

--- In DigitalBlackandWhiteThePrint@yahoogroups.com, "Richard 
Wolfson" <rw@r...> wrote:
> hi John -
> 
> Joe's "canned" curves are a good starting point, but you may need to
> make significant changes. Here is a curve-editing procedure you may 
find
> helpful.
> 
> 1. Prepare a 26 step grayscale step wedge suitable for your
> spectrophotometer. The Photoshop gray values of the patches should 
be
> 0%, 4%, 8%, and so on, up to 100% of black.
> 
> 2. Print the step wedge through OPM using your starting "profile."
> 
> 3. Measure the luminance (L*) of the patches, import the data into
> Excel, graph the points, and compare the resulting curve to a 
luminance
> target straight line from your maximum L* (paper white, at 0% K) to 
your
> minimum L* (Dmax, at 100% K).
> 
> 4. Adjust ink levels using "free edit" in IJC. Add ink where the L* 
plot
> is above your luminance target line; remove ink where the L* plot is
> below target. You'll need to study your curves to decide which ink 
to
> vary in each part of your gray scale. Also, to get the best possible
> Dmax (i.e., lowest minimum luminance), adjust the ink mixture at 
100%
> carefully. Save the adjusted ink curves as a new "profile."
> 
> 5. Repeat steps 2 through 4 until you get the best result you can. 
When
> you're very close, you can try using IJC's "Linearize" function to 
see
> if it does any better than you can by hand.
> 
> I use an X-Rite DTP-41 strip-reading spectrophotometer for this 
kind of
> work, and I have found working toward a linear gray ramp in L* space
> works very well. 
> 
> If you don't have a spectro, you can work with a densitometer and
> convert density readings to L*, or you can work with densities 
instead
> of luminance, but in this case you should work toward a gamma curve
> target, not a straight line. If you don't have a densitometer 
either,
> you may be able to get decent results working with a scanner, but 
you'll
> be at a disadvantage, I think.
> 
> I realize this may seem a bit sketchy. Expect a fairly steep 
learning
> curve if this all seems new to you.
> 
> Richard Wolfson
> Fine Art Photographer & Digital Imaging Consultant
> 
> 
> 
>