Re:PrePress Lout and Multilingual publications

[Graham Douglas]

Hi Ian

Firstly, I have written a PostScript prolog which
outputs correct crop marks designed for printing
-- though not set using the CMYK colour space
(easily fixed). If you want a copy, mail me.

The ease of what you want to do all depends on
how much you know about prepress -- colour
separation, RIPs, trapping etc. This really is a
very complex area -- especially at the PostScript level.
(you may be expert in these areas, I don't know)

There are two excellent newsgroups:

comp.publish.prepress

where you can get lots of practical advice
on prepress issues.

comp.lang.postscript

where you can get advice on the PostScript
issues.

Firstly, for colour separation you need
scans in CMYK TIFF format -- so you'll have to
find a way to convert these to EPS since
Lout has no support for TIFF, sadly. This could
give you very large EPS files -- maybe Sam Leffler's
libtiff library could help you here --> a utility to
do CMYK TIFF -> EPS. There is a libtiff mailing
list.

Some RIPs can do RGB -> CMYK conversion
on-the-fly though the best results are obtained
by careful, professional, colour correction
in something like PhotoShop.

This is a long shot....
What you could do is investigate something
called the Open Prepress Interface (OPI) which, in effect,
puts instructions into the PostScript print stream
telling the output device (RIP) to include high-resolution
images (an OPI server sees the OPI instructions and
grabs the file, I think). You would need to get these comments
into the print stream and make Lout leave enough space
for the image. This could be very tricky...

You don't need to pre-separate the files yourself. If you
supply a composite file with everything defined in
CMYK then the separation can be done by the RIP.
(in fact it is better to do this so the *printer* can
handle the separations etc.).

You will need to get expert advice on how to correctly
define spot colours in the PostScript -- see newsgroups above.

I also recommend Adobe's web site

www.adobe.com

which contains many technical notes on prepress/PostScript
issues. In particular, research in-RIP separations/trapping etc.
Do a web search on "trapping" too. Again, trapping is
very definitely best left to experienced prepress professionals
who have specialist software for this task -- ask in
comp.publish.prepress.

An *excellent* prepress site full of great info is:

http://www.prepress.pps.com/TechReports/TechReports.htm

--> contains OPI information.

What you might like to do is to add CMYK
colour support to all the Lout packages and
perhaps change Lout's standard PostScript prolog
(buried in the C source -- though I think it should
be a single separate resource file).

I hope the above is a useful start.

In particular:

> Eg, if I have a grey (ie real grey on the finished
> page) box with  red text on. Using the hack as I have described, I
> would get the grey box put on the black plate, but seeing that the
> red text didn't match, lout would output it as white. Will that remain
> a grey square on the black plate film, or will it end up grey with
> white writing inscribed in it? I'm not sure whether the white letter
> spaces left in the grey box, for the red letters may not be what is needed
> anyway.

You're talking about "knockout" here -- so that the
Red does not overprint onto the grey. Yes, on the black plate you
need to have a white space where the Red letter is to appear otherwise
your nice Red would print on top a grey background giving ugly results.
Note also the order in which the CMYK inks are printed. I'm not expert in
this so don't quote me -- go to the comp.publish.prepress newsgroup.
Black (K) is, I think, printed last. Sometimes printers have a preferred
inking order -- so let *them* do the separations. Most bigger printers
have prepress facilities in-house or send the work out to bureau who
knows their presses etc.

Further, in order for the Lout pages to be imposed for press
the PostScript will, in most cases, have to be page independent.
(ie ALL downloaded fonts in the prolog or included on every
page (massive files)). I'd *strongly* recommend converting
Lout's PostScript to PDF via Acrobat Distiller (but get advice
on the detailed CMYK colour issues).

And >>**ALWAYS**<<  talk to your printer and/or
prepress bureau before you start.

I hope this is a helpful start.

Graham