Path: utzoo!attcan!uunet!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: <14809@well.UUCP> Date: 3 Dec 89 17:48:47 GMT Reply-To: Jef Poskanzer Followup-To: no followups, please Organization: Paratheo-Anametamystikhood Of Eris Esoteric, Ada Lovelace Cabal Lines: 115 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) Drawing three-dimensional objects on a two-dimensional screen. The simple answer is, you divide by the depth. For a more verbose explanation, see any of the above references. 2) 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. 3) Converting color into grayscale. The NTSC formula is: luminosity = .299 red + .587 green + .114 blue 4) 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 5) Image manipulation software. There are a number of free toolkits for converting from one image format to another, doing simple image manipulations such as size scaling, plus the above-mentioned 24 -> 8, color -> gray, gray -> b&w conversions. Here are pointers to some of them: PBMPLUS, by Jef Poskanzer. Comprehensive format conversion and image manipulation package. Version of 22nov89 was posted to comp.sources.misc. The latest version is always available via FTP as expo.lcs.mit.edu:contrib/pbmplus.tar.Z and ftp.ee.lbl.gov: pbmplus.tar.Z. Also available in your nearest X.V11 source tree or comp.sources.misc archive. Utah RLE Toolkit. Conversion and manipulation package, similar to PBMPLUS. Available via FTP as cs.utah.edu:pub/toolkit-2.0.tar.Z and ucsd.edu:graphics/utah-raster-toolkit.tar.Z. Fuzzy Pixmap Manipulation, by Michael Mauldin . Conversion and manipulation package, similar to PBMPLUS. Available via FTP as nl.cs.cmu.edu:/usr/mlm/ftp/fbm.tar.Z and ucsd.edu:graphics/ fbm.tar.Z, and also in your nearest comp.sources.unix archive. Img-whatnot, by Paul Raveling . Reads and writes its own image format, displays on an X.V11 screen, and does some image manipulations. Available via FTP as expo.lcs.mit.edu:contrib/ Img.tar.Z, and venera.isi.edu:pub/Img.tar.Z along with a large collection of color images. Xim, by Philip R. Thompson. Reads and writes its own image format, displays on an X.V11 screen, and does some image manipulations. Available via FTP as expo.lcs.mit.edu:contrib/xim3c.tar.Z. xloadimage, by Jim Frost . Reads in images in various formats and displays them on an X.V11 screen. Available via FTP as expo.lcs.mit.edu:contrib/xloadimage.tar.Z, and in your nearest comp.sources.x archive. TIFF Software, by Sam Leffler . Nice portable library for reading and writing TIFF files, plus a few tools for manipulating them and reading other formats. Available via FTP as okeeffe.berkeley.edu:pub/tiff.tar.Z. HIPS, from the Human Information Processing Laboratory at NYU. For availability contact Michael Landy, Psychology Dept., NYU, 6 Washington Place, Room 980, New York NY 10003. This package is *not* free. ALV Toolkit, available via email to alv-users-request@cs.bris.ac.uk. 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: expo.lcs.mit.edu 18.30.0.212 ftp.ee.lbl.gov 128.3.254.68 cs.utah.edu 128.110.4.21 NL.CS.CMU.EDU 128.2.222.56 venera.isi.edu 128.9.0.32 okeeffe.berkeley.edu 128.32.130.3 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. Brought to you by Super Global Mega Corp .com