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Article #5675

Re: Converting X color (24 bits color) image to postscript.

#5675
From: Chris Lilley
Date: Thu, 12 Nov 1992 21:45
41 lines
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In article <1992Nov10.194925.15996@cc.umontreal.ca> latendrm@ERE.UMontreal.CA (Latendresse Mario) writes:

>I have been looking around to find a program to convert
>images, dumped by the xwd program from a 24 bits color
>display, into PostScript (Level 2).

Well converting it to a PS file that *prints* on a level 2 printer is
one thing. Finding a program that *uses* the level 2 features is
another. Were you thinking of the compression or the device
independent colour aspects of Level 2?

Anyway, to make your file try:

xwd -nobdrs | xwdtopnm | pnmtops > file.ps (or pipe straight to your
printer)

You may want to remove gamma correction from your ppm image before
conversion to PS (printers don't need gamma correction).

Note that this process uses the simple minded (1-R)(1-G)(1-B) formula
so the colours will be quite different in print from the screen.

If you want to use the Level 2 image operator and set up a calibrated
RGB space you will need to know the RGB and white chromaticities of
your monitor, and its gamma. 

Has anyone written a program that takes a ppm file and this info and
generates a Level 2 PostScript representation like this? I understand
what it has to do, but wouldn't call myself a programmer.




--
Chris Lilley
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Technical Author, ITTI Computer Graphics and Visualisation Training Project
Computer Graphics Unit, Manchester Computing Centre, Manchester, UK
Internet:   lilley@cgu.mcc.ac.uk        Janet:   lilley@uk.ac.mcc.cgu
Voice:      +44 (0)61 275 6095          Fax:     +44 (0)61 275 6040
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Path: arc1-ca.pugleaf.net!sparky!uunet!mcsun!uknet!mucs!lilleyc
From: lilleyc@cs.man.ac.uk (Chris Lilley)
Newsgroups: comp.lang.postscript
Subject: Re: Converting X color (24 bits color) image to postscript.
Keywords: Preview
Message-ID: <6738@m1.cs.man.ac.uk>
Date: 12 Nov 92 21:45:08 GMT
References: <4078@sapwdf.UUCP> <1992Nov10.194925.15996@cc.umontreal.ca>
Sender: newsman@cs.man.ac.uk
Organization: Dept Computer Science, University of Manchester, U.K.
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