Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!cs.utexas.edu!usc!apple!well!jef
From: jef@well.UUCP (Jef Poskanzer)
Newsgroups: comp.graphics
Subject: Frequently asked questions - weekly automated posting.
Message-ID: <14536@well.UUCP>
Date: 12 Nov 89 16:47:53 GMT
Reply-To: Jef Poskanzer <jef@well.sf.ca.us>
Followup-To: no followups, please
Organization: Paratheo-Anametamystikhood Of Eris Esoteric, Ada Lovelace Cabal
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This message is automatically posted once a week in an effort to cut
down on the repetitive junk in comp.graphics.  If you have answers to
other frequently asked questions that you would like included in this
posting, please send me mail.  If you don't want to see this posting
every week, please add the subject line to your kill file.  Thank you.
---
Jef

      Jef Poskanzer  jef@well.sf.ca.us  {ucbvax, apple, hplabs}!well!jef
                        "...Is this a trick question?"

- - - - - - - - - -

0) General references for graphics questions:

    Fundamentals of Interactive Computer Graphics, J. D. Foley and A. van Dam,
      Addison Wesley, ISBN 0-201-14468-9
    Principles of Interactive Computer Graphics 2nd Ed., Newman and Sproul,
      McGraw Hill, ISBN 0-07-046338-7
    Procedural Elements for Computer Graphics, David F. Rogers, McGraw Hill,
      ISBN 0-07-053534-5
    Mathematical Elements for Computer Graphics 2nd Ed., David F. Rogers and
      J. Alan Adams, McGraw Hill, ISBN 0-07-053530-2
    Applied Concepts in Microcomputer Graphics, Bruce Artwick, Prentice-Hall,
      ISBN 0-13-039322-3


1) Quantizing 24 bit images down to 8 bits.  Find a copy of "Color
Image Quantization for Frame Buffer Display" by Paul Heckbert, SIGGRAPH
'82 Proceedings, page 297.  There are other algorithms, but this one
works well and is fairly simple.


2) Converting color into grayscale.  The NTSC formula is:

    luminosity = .299 red + .587 green + .114 blue


3) Quantizing grayscale to black&white.  The only reference you need
for this stuff is:

    Digital Halftoning, Robert Ulichney, MIT Press, ISBN 0-262-21009-6


4) How to convert from one image format to another.  There are a number
of free toolkits for doing image format conversions, simple image
manipulations such as size scaling, plus the above-mentioned 24 -> 8,
color -> gray, gray -> b&w conversions.  Here are pointers to three of
them:

    Utah RLE Toolkit.  Available via FTP on cs.utah.edu.

    Fuzzy Pixmap Manipulation, by Michael Mauldin.  Version 0.9 was posted
    to comp.sources.unix, and is available from c.s.u archives.  The latest
    version is always available via FTP in nl.cs.cmu.edu:/usr/mlm/ftp.

    PBMPLUS, by Jef Poskanzer.  Version of 13sep89 was posted to
    alt.sources.  The latest version is always available via FTP as
    expo.lcs.mit.edu:contrib/pbmplus.tar.Z.

Don't forget to set binary mode when you FTP tar files.  For you MILNET
folks who still don't have name servers, the IP addresses are:

    cs.utah.edu		128.110.4.21
    NL.CS.CMU.EDU	128.2.222.56
    expo.lcs.mit.edu	18.30.0.212

Please do *not* post or mail messages saying "I can't FTP, could
someone mail this to me?" There are a number of sites that archive the
sources newsgroups and make the contents available through an automated
mail query system.

If you bring one of these packages to someplace far away, such as the
West Coast or Europe, consider making it available for FTP from your
site and letting me know so I can add you to this posting.