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.

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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.

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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.
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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