Digital BW, The Print

Can someone direct me to a web page where I might find a fairly
detailed tutorial on using/modifying Photoshop curves for use in
controlling ink positions?  I get it on a very high level but in terms
of nuts and bolts on how to choose/tweak points in each channel is
beyond me.

Thanks,
Earl

--- In DigitalBlackandWhiteThePrint@yahoogroups.com, "esharamaki"
<esharamaki@...> wrote:
>
> Can someone direct me to a web page where I might find a fairly
> detailed tutorial on using/modifying Photoshop curves for use in
> controlling ink positions?  I get it on a very high level but in terms
> of nuts and bolts on how to choose/tweak points in each channel is
> beyond me.
> 
> Thanks,
> Earl
>

Earl,

I'm not sure what you mean by ink "positions".  I assume you are
looking for a way to use curves in individual channels to balance
color and control contrast.  

This isn't exactly a tutorial, but it is a chapter from a book that
discusses the use of curves in individual channels for correcting
color and contrast.  He avoids the use of composite curves (ie, the
master RGB or CMYK curve, for example).  This method can be used in
RGB, CMYK or Lab.  It is fairly in-depth and effective, but takes
practice.  The essence is selecting appropriate highlights, shadows,
known colors or neutrals (using the info palette in Photoshop) or
inferring which colors are incorrect, then adjusting them so they are
within reason.  

Dan Margulis is a controversial figure, and while I don't agree with
some of his positions, he has a tremendous amount of usable and
effective knowledge.  The below is a link to some free chapters in PDF
format.  Click the link for Chapter 3 - Color by the Numbers, from
Professional Photoshop 5th Edition.  

http://www.ledet.com/margulis/articles.html


I hope this is what you were looking for.  

Lou

Lou,
Thanks for the reply.  I believe before using printfix pro or
spectrophotomer to create icc for color managed workflow, curves were
used to smooth out transition of ink in a step wedge.  If you look at
some of the curves that were (are) available for MIS inks, the RGB
channel is a straight diagonal line, while the red, green blue
channels have odd shaped curves.  These curve channels control which
positions in the printer (K,C,LC,M,LM,Y,etc) lay down ink at which
point in the step wedge (or any picture for that matter) when applied.

I'm using the UT-3D inkset in my R220 to try and learn.  For starters,
I tried using printfix pro (spyderprint) to print out targets, read
and create profile.  The test print showed some abrupt changes.  When
I used the curves from Paul Roark, and embedded into profile using QTR
create tool, the transitions were much smoother.  So, I'm interested
in learning how to make/tweak these curves on my own for the various
papers I use.

Thanks for the link though.  I still intend to check it out further.

--- In DigitalBlackandWhiteThePrint@yahoogroups.com, "esharamaki"
<esharamaki@...> wrote:
>
> Lou,
> Thanks for the reply.  I believe before using printfix pro or
> spectrophotomer to create icc for color managed workflow, curves were
> used to smooth out transition of ink in a step wedge.  If you look at
> some of the curves that were (are) available for MIS inks, the RGB
> channel is a straight diagonal line, while the red, green blue
> channels have odd shaped curves.  These curve channels control which
> positions in the printer (K,C,LC,M,LM,Y,etc) lay down ink at which
> point in the step wedge (or any picture for that matter) when applied.
> 
> I'm using the UT-3D inkset in my R220 to try and learn.  For starters,
> I tried using printfix pro (spyderprint) to print out targets, read
> and create profile.  The test print showed some abrupt changes.  When
> I used the curves from Paul Roark, and embedded into profile using QTR
> create tool, the transitions were much smoother.  So, I'm interested
> in learning how to make/tweak these curves on my own for the various
> papers I use.
> 
> Thanks for the link though.  I still intend to check it out further.
>

Earl,

I totally misunderstood what you were looking for.  I understand now.
 I believe Paul Roark has some great information on his website for
what you want; I'm just not sure where to find it.

Lou