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Offset printers need separate camera-ready copies for each ink
they will use in printing a document. Aurora is a PostScript
program for producing colour separates from a colour PostScript
document. Aurora can be run from any type of computer, as it
depends only on a black-and-white PostScript printer for its
execution. It is capable of handling colour images as well as
ordinary graphics, though image handling is very slow.
=============================================================================
CONTENTS
========
The Aurora distribution consists of the files
README This file.
aurora The Aurora PostScript program.
auroratx.ps A description of how Aurora works, its limitations, and
examples showing what it will do. This document is
suitable for printing on a colour printer, a Level 2
machine, viewing with a PostScript interpreter, or as
a last resort, printing on an old Level 1 machine.
The last page, containing several images, is extremely
slow to output.
cyan These four files allow selection of the primary colour
magenta for a particular run of Aurora. Any colour used in
yellow a document will be separated into these components, and
black the amount of the selected primary will be output.
red These three files are examples of how to select custom
green colours. When used with Aurora, only precise matches
blue to a custom colour are output (either as full black or
as a shade of gray).
60.lpi When using the CMYK colours, it is useful to set up
71.lpi different screens for halftones of the different
85.lpi primaries. These files contain instructions obtained
from the Adobe file server for establishing suitable
screens for a desired dot density. The parameters
used in these files may vary between machines, and
you may find it necessary to consult the PPD file
appropriate to your machine from the Adobe file server
for more suitable numbers for setting colour screens
on your hardware.
=============================================================================
USAGE
=====
It is necessary to send to the PostScript printer the file
"aurora", followed by a colour primary selection, optionally a
screen specification, and then the document itself. With some
operating systems, it is best to join (or concatenate) the separate
files into one before despatch to the printer. They must be
treated as a single job by the PostScript printer.
This procedure must be followed for each desired separate.
For example, the files
aurora magenta 60.lpi mydoc
would be sent as a single file to the printer to print the magenta
separate of "mydoc", using a 60 lines per inch screen.
=============================================================================
Aurora is available by anonymous FTP from "ftp.adfa.oz.au" in
directory "pub/postscript".
Aurora may not be used for commercial purposes without the consent
of the author. It may be freely transmitted provided the authorship
and copyright notice is retained unmodified.
Graham Freeman
gfreeman@cs.adfa.oz.au
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