Digital BW, The Print

Any pointers on how to do this?
I have an Epson 1160 with VTBlax dedicated B&W inks. How does one 
determine what the curves should look like for each of the 4 inks (if 
indeed all inks should be on)? I know how to set the ink limits but 
after that the ink shapes section is a bit of a mystery. I tried 
using the Black ink, dark grey ink etc sample curves and just got a 
very dark print.
Is there a simple step by step way of doing this that would at least 
get me to a reasonable starting point? 

I realise I might be missing something obvious (it has been known) 
but all and any help would be appreciated.

Hello John,

The way you mentioned , by using the starting curves is the best way to
start, In not familiar with the VTBlax inks so they might have a heavy
density.
Once you select the starter ink shapes,. E.g.  Black, Dark Grey, Mid Grey,
and Light grey,.  Your next step is to print a tweaked ink target.
So this sounds like where you are..  If this target is too dark. The next
step is to reduce the scale of these inks.

You will notice in the ink shape editor, that when you edit one of these
inks.  There will be a vertical slider to the right of the editing window,
this slider controls the scale of each ink ( how much of the ink it uses).
So as you will see by moving the slider down, the ink shape you built will
scale up and down as well.

So the next step would be to simple scale down the Dark Grey and Mid grey
10-25% I¹d leave the Black and the light grey as is for now.  After a  one
or two adjustments you should be ready for Linearization.

What you are looking for prior to Linearization  is a good separation of the
steps of the target, Linearization will do the rest.

Joe



On 1/5/05 8:08 AM, "johndavidgill2003" <jdgill@...> wrote:

> 
> Any pointers on how to do this?
> I have an Epson 1160 with VTBlax dedicated B&W inks. How does one
> determine what the curves should look like for each of the 4 inks (if
> indeed all inks should be on)? I know how to set the ink limits but
> after that the ink shapes section is a bit of a mystery. I tried
> using the Black ink, dark grey ink etc sample curves and just got a
> very dark print.
> Is there a simple step by step way of doing this that would at least
> get me to a reasonable starting point?
> 
> I realise I might be missing something obvious (it has been known)
> but all and any help would be appreciated.
> 
> 
> 
> 




[Non-text portions of this message have been removed]

--- In DigitalBlackandWhiteThePrint@yahoogroups.com, Joe Berndt 
<joeberndt@v...> wrote:
 
> You will notice in the ink shape editor, that when you edit one of 
these
> inks.  There will be a vertical slider to the right of the editing 
window,
> this slider controls the scale of each ink ( how much of the ink it 
uses).
> So as you will see by moving the slider down, the ink shape you 
built will
> scale up and down as well.
> 

Joe, 
The black ink curve has no vertical slider (the other 3 do) but the 
black ink curve only has the horizontal slider.

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

> -----Original Message-----
> From: johndavidgill2003 [mailto:jdgill@...] 
> Sent: Wednesday, January 05, 2005 11:08 AM
> To: DigitalBlackandWhiteThePrint@yahoogroups.com
> Subject: [Digital BW] IJC/OPM - Creating Curves from scratch
> 
> Any pointers on how to do this?
> I have an Epson 1160 with VTBlax dedicated B&W inks. How does 
> one determine what the curves should look like for each of 
> the 4 inks (if indeed all inks should be on)? I know how to 
> set the ink limits but after that the ink shapes section is a 
> bit of a mystery. I tried using the Black ink, dark grey ink 
> etc sample curves and just got a very dark print.
> Is there a simple step by step way of doing this that would 
> at least get me to a reasonable starting point? 
> 
> I realise I might be missing something obvious (it has been 
> known) but all and any help would be appreciated.
>

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
> 
> 
> 
>