Digital BW, The Print

--- In DigitalBlackandWhiteThePrint@yahoogroups.com, "d.burges"
<davidburges@...> wrote:
>
> Hi, Does anyone have an answer to obtaining neutral tone B+W images
> when printing as a CMYK file. I'm a photographer in the UK putting
> together a 62 page photobook for a client who wants the book in B+W,
> the company which produce the books for me need  pdf files created in
> photoshop coverted to CMYK as they print on a commercial printing press,
> I've just had the books back and many of the pages have printed with
> slightly differing hues, mainly yellow, some blue. Having read many
> posts it would seem it is very hard to obtain neutral tones due to the
> difficulty of mixing the CMY inks to produce neutral B+W, however I'm
> hoping there is an answer out there somewhere! David
> www.blinkweddings.co.uk
>

David, 
I just sent such a job to press.  Came back totally neutral using CMYK
builds.  Black only can sometimes look a little weak on press, and
since it is only a single plate, can also look at bit "grainy",
especially if you have color images on the same spread.  

If you are starting with RGB files, you can separate to a Rich Black
using either Heavy GCE or Max GCR (gray component replacement).  This
will give you a heavy black plate, and a "bump" in the CMY plates for
extra richness.  Using heavy or max GCR insures that a LOT of black in
is laid down, so it is unlikely you will have a color shirt on press.
 A blend of 50c/40m/40y combined with about 90-100K in the darkest
black areas will give you a very solid rich black.  Most presses are
pretty close to dead neutral with the above CMY values in the midtones.  

Since you don't want or need color, you can actually use Photoshop's
custom CMYK for this quite effectively.  Go to Color Settings, in the
CMYK dropdown box, select Custom CMYK, select Maximum GCR, 100 Black
Ink Limit, 300 Total Ink Limit, and enter 40 or 50 in the UCA Amount
box.  UCA is "undercolor addition" which throws a blend of CMY into
the mix, especially in the shadows.  Entering a value of 50 will give
you about 50c/40m/440y in the darkest shadows.  Click OK, then, when
you get back to the Color Settings dialog box, DO NOT CLICK SAVE, but
go to the CMYK dropdown box again and from there, click on Save CMYK.
 Name it whatever you want (ie, MAX-K_with50UCA) and click the Save
button.  This will create an ICC profile that you can use in the
future for conversions from Photoshop.  When you get back to the Color
Settings dialog, click CANCEL, since your probably do NOT want to save
this new profile as part of your standard settings in Photoshop.  

If you are doing the CMYK conversions, this will give you a very
strong Black with a bump of CMYK to add depth and density.  When you
create your PDF, you may wish to strip all profiles and send them an
untagged CMYK PDF file, so they do "reseparate" the file and screw up
the great blacks you created.  If they do reseparate, who knows what
they might do?

If you are starting with CMYK files, you probably need to have a
discussion with your printer to find out their formulas for neutrality
on press.  I'd still strive for heavy usage of black inks and much
lower values for CMY inks.  Whether you are in the US, UK, or far
east, most presses come pretty close to neutral with a mix of
50c/40m/40y.  The kicker is at the light end where being slightly off
neutral is more evident to the eye.  Using heavy or Max GCR is a good
way to go if you want to stay close to the neutral axis.  If you want
toned prints (brown, sepia, etc) it can still be a decent option,
since the heavy black should keep color drift to a minimum.  

Lou