Digital BW, The Print

OK, I've kicked off the process of making some curves for UT2 inks 
with Hahnemuehle Fineart Pearl paper, starting with the Premier Semi 
Gloss curves on Paul's website. First thing - print a stepwedge, have 
a look at it and examine the curves in photoshop.

The neutral curve looked pretty neutral, the steps between 95% and 
70% looking a bit light as best I could judge by comparison to my 
monitor. I know I could simply do a 'create ICC' at this point and 
have done with it, but I want to understand...

So I take a look at the curves. I've read Dirk Hobman's explanation 
of how to interpret these from the MIS website. I'm rather surprised 
by two things. First, the neutral curves for Eboni ink have a blue 
curve that is almost flat across the top of the grid. My 
interpretation of this is that the light grey doesn't get used with 
this curve. Second, the version of the curves for Photo Black has the 
blue curve dropping to zero at the left-hand end of the grid.

From Dirk's explanation, I understood that 'all inks at zero' was 
needed so the Epson driver would know to get the black ink working... 
so where does that leave the Eboni curves? Is the light grey more or 
less redundant? And what tells the driver to bring in the black?

This is giving me a headache!

Any help appreciated,
Ben

--- In DigitalBlackandWhiteThePrint@yahoogroups.com, "benc_1972" 
<ben@...> wrote:
>
> OK, I've kicked off the process of making some curves for UT2 inks 
> with Hahnemuehle Fineart Pearl paper, starting with the Premier 
Semi 
> Gloss curves on Paul's website. First thing - print a stepwedge, 
have 
> a look at it and examine the curves in photoshop.
> 
> The neutral curve looked pretty neutral, the steps between 95% and 
> 70% looking a bit light as best I could judge by comparison to my 
> monitor. I know I could simply do a 'create ICC' at this point and 
> have done with it, but I want to understand...
> 
> So I take a look at the curves. I've read Dirk Hobman's explanation 
> of how to interpret these from the MIS website. I'm rather 
surprised 
> by two things. First, the neutral curves for Eboni ink have a blue 
> curve that is almost flat across the top of the grid. My 
> interpretation of this is that the light grey doesn't get used with 
> this curve. Second, the version of the curves for Photo Black has 
the 
> blue curve dropping to zero at the left-hand end of the grid.
> 
> From Dirk's explanation, I understood that 'all inks at zero' was 
> needed so the Epson driver would know to get the black ink 
working... 
> so where does that leave the Eboni curves? Is the light grey more 
or 
> less redundant? And what tells the driver to bring in the black?
> 
> This is giving me a headache!
> 
> Any help appreciated,
> Ben
>


OK, I've figured out part of it - it's not light grey in the yellow 
position, it's sepia (doh!). Still not sure howe the driver knows to 
turn on the black though!
Ben

>... Still not sure how the driver knows to turn on the black ...

The driver looks at the RGB values and starts to substitute black as the 3
curves approach the black point.  Take a look at some of the UT-3D curves
for glossy paper and you'll see where I have to turn the blue curve upward
to stop the Eboni from being injected.  In UT2 curves, when the red and
green curves are very close to black, the blue curve (sepia ink) becomes, in
effect, the black ink curve.

Paul
www.PaulRoark.com

--- In DigitalBlackandWhiteThePrint@yahoogroups.com, "Paul Roark" 
<paul.roark@...> wrote:
>
> 
> 
> >... Still not sure how the driver knows to turn on the black ...
> 
> The driver looks at the RGB values and starts to substitute black 
as the 3
> curves approach the black point.  Take a look at some of the UT-3D 
curves
> for glossy paper and you'll see where I have to turn the blue curve 
upward
> to stop the Eboni from being injected.  In UT2 curves, when the red 
and
> green curves are very close to black, the blue curve (sepia ink) 
becomes, in
> effect, the black ink curve.
> 
> Paul
> www.PaulRoark.com
>


Paul,

Thanks very much for explaining this,I've looked at the curves and I 
see what you mean. And I guess this answers my question about what 
makes the black ink come in with Eboni on glossy paper too - nothing. 
The idea that you could get black without the black ink is somewhat 
counter-intuitive to me!

Best regards,
Ben

>The idea that you could get black without the black ink is 

>somewhat counter-intuitive to me!

 

I found that there was no advantage to PK with the UT2 inkset.  So, you'll
find few curve for that ink.  The 2 dark grays do a fine job.

 

Paul

www.PaulRoark.com <http://www.paulroark.com/>  

 

 

  _____  

From: DigitalBlackandWhiteThePrint@yahoogroups.com
[mailto:DigitalBlackandWhiteThePrint@yahoogroups.com] On Behalf Of benc_1972
Sent: Friday, November 24, 2006 12:18 PM
To: DigitalBlackandWhiteThePrint@yahoogroups.com
Subject: [Digital BW] Re: UT2 curves - how does this work?

 

--- In DigitalBlackandWhit
<mailto:DigitalBlackandWhiteThePrint%40yahoogroups.com>
eThePrint@yahoogroups.com, "Paul Roark" 
<paul.roark@...> wrote:
>
> 
> 
> >... Still not sure how the driver knows to turn on the black ...
> 
> The driver looks at the RGB values and starts to substitute black 
as the 3
> curves approach the black point. Take a look at some of the UT-3D 
curves
> for glossy paper and you'll see where I have to turn the blue curve 
upward
> to stop the Eboni from being injected. In UT2 curves, when the red 
and
> green curves are very close to black, the blue curve (sepia ink) 
becomes, in
> effect, the black ink curve.
> 
> Paul
> www.PaulRoark.com
>

Paul,

Thanks very much for explaining this,I've looked at the curves and I 
see what you mean. And I guess this answers my question about what 
makes the black ink come in with Eboni on glossy paper too - nothing. 
The idea that you could get black without the black ink is somewhat 
counter-intuitive to me!

Best regards,
Ben

 



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