Hello Henry and all,
If you'd like to do further reading on this topic, we have a Virtual Knowledge Base article that covers many of the variables that may come into play when outputting black information.
AE0248 Printing Rich Black, Pure Black, and Print Black
Problem Description:
I am having difficulty with getting my blacks to print a true black.
Sometimes black in my print jobs and exported PDF files appear more
like gray even though I've set black to 100%. Why is there a difference
between RGB black (0,0,0), CMYK black (0,0,0,100), and rich black
(100,100,100,100)?
Background:
The key thing to remember when working with black regions in your
layout is that is it is possible to have black mismatches between
imported images created in other applications and objects created in
QuarkXPress, even though you have only chosen a straight CMYK black for
QuarkXPress objects or text. These mismatches occur when converting RGB
black to CMYK black, when designing using the straight CMYK black, or
when building rich blacks. Mismatches between different types of black
may be difficult to see on a monitor, but you can often detect
differences in display when you view the blacks next to each other. For
example, when RGB black (R0, G0, B0) is
converted to 4-color CMYK black in PhotoShop, the RGB black information
is transformed to C-63, M-52, Y-51, K-100 in the CMYK color space.
Note!:
The CMYK black build will be entirely dependent on the working CMYK
profile chosen in Photoshop’s Color Settings. This is in addition to
either the source profile of the image or the working RGB profile
chosen in Photoshop’s Color settings.
When
an image is printed with these values, the resulting black prints
noticeably darker than a CMYK black with values of of 0,0,0,100. A rich
black will result in a darker, shinier black at the press. A straight 100% black will result in a duller, matte-like finish.This occurs because less ink is being laid down on a particular region of a page.
If
you are working in a color-managed workflow, black information can
undergo color transforms if the profile for the source and target
devices have significant conversions defined for black. For more
information on color managed workflows please refer to: the QXP User Guide PDF file (located in the Documents folder of your QuarkXPress folder), pp.142 ff.
Note!:
Ultimately you will want to consult with your prepress department or
with your service burreau customer service representative to determine
how you should be defining your rich black or regular black information
for specific jobs.
More Information:
Much information is available online relating to creation and output of
Rich Black. While these links to other vendor sites are not a complete
list, we have referenced these as a service to our customers:
From the OCE web site
http://dl.oce.com/downloads/downloadsave.asp?FilePath=%5CEn%5CPdf%5Cproducts%5Ccpsrichblackwpp.pdf&filename=cpsrichblackwpp.pdf
http://outskirtspress.com/admin/***/Images%20in%20a%20Digital%20World.pdf
From the Adobe web site:
http://livedocs.adobe.com/en_US/InDesign/5.0/help.html?content=WS7E8089AA-F584-46b0-8E67-DAA2ED79BE4B.html