[texhax] Using color.

Pierre MacKay mackay at cs.washington.edu
Sat Dec 13 05:52:16 CET 2003

This gets beyond the actual use of TeX, but there are probably others
beside myself who need to find some way to get at the full range of
color out of TeX documents.

For a year or so I have done fairly well by getting the cmykcolor values
equivalent to a Pantone color and using a dvips special to
setcmykcolor.  But now I am being required to use spot color separations
and I am constantly frustrated by the absence of useful (got that? USEFUL)
documentation.  Yes I have RTFM.  I have damn near cried myself to sleep
over the Red Book, which gives a fairly simple formula

[/Separation (spot color) alternativeSpace tintTransform]setcolorspace

I can do that.  I am pretty sure I am doing it right.  But I can't
make it do anything.  If I try to set up anything, even /DeviceCMYK,
using the setpagedevice dictionary operator (All of this is done in
dvips specials) Ghostscript 7.07 gives me its usual errors and dies.
The closest I have ever got is a reference out of gs_lev2.ps to
.setseparationspace (note the dot in front of that---does that tell me
that GhostScript is just not ready to do separations yet?)  gs_init.ps
tells me very clearly that DeviceN is not available yet.

I have read Adobe publication 5044, which doesn't help, because the
model for a /Separation used there doesn't look like the one in the Red book.
Nor does the specific special Adobe note on /DeviceN color spaces.  They
work on the screen, but give virtually no indication of what makes them
work.  GhostScript actually uses the model in Red Book p. 242, but I can't
make it operational.

I know this isn't really the TeX part of TeXhax, but there is probably
no other group that might actually know how to get spot colors working.
All the published books I have seen give you the advice that you
can do it by pulling down menu XXX in Quark and pressing key F7.  Tex
users will understand that that is no help at all.  The whole point
is NOT to use Quark or any of the other garguantuan and hugely expensive
packages.  Color support is supposed to be part of Postscript, and it
should be accessible by entering dvips specials. Spot colors for in-RIP
separation ought to be particularly easy, because they don't do anything
until you run the file through the RIP.  On your screen, the /Separation
formula is supposed to see that a computer is not a spot color device and
to move on to try cmykcolor, if DeviceCMYK is the alternative ProcessColor

This is a cry of desperation at the moment.  A recommendation to a book
that actually gives PostScript coding examples is what is needed.  If
the book simply says that you pull down Menu XXX in Quark, it is worse
than useless.  Why does Adobe not give coding exsamples which actually
follow its own Red Book?  


Pierre MacKay

PS, a better mechanism than editing in EMACS might be used to add
Structure Comments such as DocumentCustomColors and DocumentProcessColors.

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