Graphics Muse Issue 20
Author: Michael J. Hammel
Description: The Monthly Column of Computer Graphics for Linux Systems.

#### "Linux Gazette...making Linux just a little more fun!"

Graphics Muse

| Set your browser as wide as you'd like now. I've fixed the Muse to expand to fill the available space! © 1997 by mjh

| muse: v; to become absorbed in thought n; [ fr. Any of the nine sister goddesses of learning and the arts in Greek Mythology ]: a source of inspiration elcome to the Graphics Muse! Why a "muse"? Well, except for the sisters aspect, the above definitions are pretty much the way I'd describe my own interest in computer graphics: it keeps me deep in thought and it is a daily source of inspiration. [Graphics Mews] [Musings] [Resources]

his column is dedicated to the use, creation, distribution, and discussion of computer graphics tools for Linux systems.
The format of this months column has changed just a tad. I rebuilt my template for the column using Netscape's Page Composer, part of the Communicator 4.01 Preview Release 6. There are lots of little things I don't like about Communicator but the Page Composer is quite nice. Its the first WYSIWYG HTML editor I've used on Linux that I've really liked. I intend to do many of my pages using it from now on. To be fair to Communicator, it is a preview release (once known as Beta, but I guess that has bad connotations now). I've always been pleased with Netscape's products. If I could just get them to publicly support Linux I'd be happier. Anyway, once the little annoying aspects are cleared up the 4.x release should be quite a boost to Netscape's product line.
During the month of July I was finishing up a major X application for my employer (EMASS, Inc, a division of Raytheon/E-Systems/TI/and who knows what else). One of the last things I had to do was port the application to a slew of Unix platforms. Well, the ports were pretty easy - it was just a matter of getting the build environment set up right - but I had lots of free time to burn while some compiles were running. Fortunately I was able to log in from home to do these, so I started to look at a few graphics applications that I've been meaning to get to for some time. The first is Image Alchemy, a commercial product from Handmade Software that provides extensive image conversion capabilities. I'd long ago promised Hap Nesbitt of Handmade Software that I would do the review. My apologies to him and Handmade for taking so long to get around to it.
The next package is ImageMagick. I've seen the posts for this package on comp.os.linux.announce many times and have heard lots of good things about the package. I decided it was time to take a closer look.
Finally, I decided to take a look at a tool thats been around for awhile but that hasn't really been discussed much in the forums that I frequent: Geomview. A quick glance at the pre-built binary really caught my eye. This is a tool with a lot of potential.

In this months column I'll also be covering:

- Is VRML ready for Prime Time?
- In Q and A: how do you turn TGA files from POV-Ray into an animation?

Oh, and the image on the right, Graphics for the Masses, was created as a demonstration of what can be done with the GIMP. It was enough to convinve the Linux Journal that I could do the cover for their November Graphics issue using this handy Photoshop clone. The final cover art doesn't look anything like this one, however. It was just a way of showing off what is possible. If anyone else needs a cover done, feel free to drop me a line!

Disclaimer: Before I get too far into this I should note that any of the news items I post in this section are just that - news. Either I happened to run across them via some mailing list I was on, via some Usenet news group, or via email from someone. I'm not necessarily endorsing these products (some of which may be commercial), I'm just letting you know I'd heard about them in the past month.

I ran across this in the GIMP Developers mailing list. Unfortunately, I forgot to save the attribution. My apologies to the original poster of the message. I've been reading some of the W3 specs recently, and I've come across some good stuff. I'm impressed - until recently it seemed like the W3 either wouldn't or couldn't get their act together, but now they seem to be putting out genuinely useful specifications. Anyway, the one with perhaps the greatest relevance to GIMP users is the sRGB standard, which specifies how images should look when displayed on the Internet. If you're interested at all in gamma correction and monitor color spaces, take a look at: http://www.w3.org/pub/ WWW/Graphics/Color/sRGB.html If you're not familiar with the color management literature, some of it will be hard going, but it might be worthwhile anyway. For people who are not intimately familiar with CIE color spaces and all that stuff, the bottom line of sRGB is that the default gamma value for Gimp should be 1.0 (as indeed it is in 0.99.10). For people that have calibrated monitors (most likely a tiny fraction of Gimp users), it would be appropriate to use some form of color management technology (I think some of the new X's have color management defined, but I'm not sure how good it is) and do a transformation from the image color space to the screen color space. However, in the absence of that, gamma correction is generally not appropriate. In the long term, it might be a good idea to add color management to the Gimp, but for now I think it's fine without. Color management tends not to work well unless it's very carefully applied - generally, something that only happens in high end environments.

## xfont3d This program is a graphical interface to Font3D (http://www-personal.ksu.edu/ ~squid/font3d.html), and requires the XForms library (http://bragg.phys.uwm.edu/xforms). The interface was developed with Font3D v1.6. Font3D generates geometry (model) files for 3D text in a variety of output formats (POV, RIB, etc.) from True Type font files. I designed xfont3d to be used as a tool mainly for POV-Ray. The built-in POV-Ray pre viewer allows you to render a sample of the font generated by Font3D. However, xfont3d supports all the output options of Font3D - you just won't be able to preview it directly from xfont3d. You can view an image of the interface and get the source code from http://cspar.uah.edu/~mallozzir I wrote the thing in about three days, so by that time I was sick of it, and hence it has not really undergone much testing Please send any bug reports or comments to mallozzir@cspar.uah.edu. Dr. Robert S. Mallozzi University of Alabama in Huntsville |  | ## GCL GCL (Graphics Command Language) is an interpreting language that is based on the data plotting library DISLIN. Version 2.2 of GCL is now released. About 400 plotting and parameter setting routines of DISLIN can be called from GCL for displaying data as curves, bar graphs, pie charts, 3D-colour plots, surfaces, contours and maps. Several output formats are supported such as X11, PostScript, CGM, HPGL, TIFF and Prescribe. Some quickplots are also added to GCL that can display data with one command. Similar to programming languages such as Fortran and C, high-level language elements can be used within GCL. These are variables, operators, array operations, loops, if and switch statements, user-defined subroutines and functions, and file I/O routines. GCL is free available for the operating systems MS-DOS, Windows 95, VMS, Linux, AIX, Digital UNIX, HP-UX and SunOS. FTP sites: ftp://ftp.gwdg.de/pub/grafik/dislin ftp://linhmi.mpae.gwdg.de/pub/dislin Home Page: http://www.mpae.gwdg.de/dislin/dislin.htm
## ImageMagick 3.8.8 The newest version of the binary distribution of ImageMagick, version 3.8.8, has been uploaded to Sunsite.. You can also get it from its primary site at ftp.wizards.dupont.com /pub/ImageMagick/linux. ImageMagick (TM), version 3.8.8, is a package for display and interactive manipulation of images for the X Window System. ImageMagick performs, also as command line programs, among others these functions: Describe the format and characteristics of an image Convert an image from one format to another Transform an image or sequence of images Read an image from an X server and output it as an image file Animate a sequence of images Combine one or more images to create new images Create a composite image by combining several separate images Segment an image based on the color histogram Retrieve, list, or print files from a remote network site The major changes in ImageMagick 3.8.8 are: PerlMagick now can interactively display an image or animate an image sequence. Subimages can now be specified in any order. For example, image.miff[3,2], image.miff[11-1], or image.miff[1,2,2,3]. Added -remote to display and animate. It allows you to send a load image command to an already running executable. Duplicate entries in an image colormap are now automatically eliminated. Display and animate now support embedded characters for the -title option (e.g. -title "%f[%s]", for filename and scene). ImageMagick supports also the Drag-and-Drop protocol form the OffiX package and many of the more popular image formats including JPEG, MPEG, PNG, TIFF, Photo CD, etc. |
## Freedom VR - Java Virtual Reality Applet Freedom VR is a photographic VR applet that was developed with Linux but also works on other flavors of Unix, the Macintosh and even Windows. It beats Quicktime VR in compression performance -- because Freedom VR uses Internet standards such as .gif and .jpeg, Freedom VR content can be produced on any platform. The developers are interested in working with other programmers to develop software for converting other VR formats such as VRML and Quicktime VR to Freedom VR. We've also written up a tutorial for taking VR photographs. Freedom VR applet: http://www.msc.cornell.edu/ ~houle/vr/freedom/ Paul and Olivia's VR Garden (produced with Freedom VR): http://www.msc.cornell.edu/ ~houle/vr/garden/ An introduction to VR photography: http://www.msc.cornell.edu/ ~houle/vr/howto/
## Jaw3DLib Jaw3DLib, a 3d programming library has been released for several platforms: linux, ms-dos, and sunos. I'd like a few alpha testers to take a look at this. An example app is included that can be easily modified. Go to: http://umn.edu/~jawed/jaw3d/ Jawed Karim jawed@tc.umn.edu http://umn.edu/~jawed
Looking for NetPBM archives? Try http://www.arc.umn.edu/ GVL/Software/pbmplus-ftp.html for a list of archive sites.
For those of you owning or otherwise interested in Connectix QuickCams: There is now a campaign attempting to convince Connectix to make the specifications for their VIDEC compression algorithm available publicly. Without the spec, it is not possible for any third-party projects (such as SANE) to support 16 bit color mode. If you want to join or learn more about the campaign, please visit: http://www.kabel.de/ ~hmueller/qc/freevidec.shtml

## IKM Interactive announces the release of axis 1.0alpha, a 3D rendering engine for Linux/SGI/Sun/Win95/WinNT.

A 3Dfx accelerated version is also available for Win95 (and possibly Linux soon). A Power Mac version is currently in development. You can download the current version from http://www.ikm.com This is an alpha release, mostly of interest to 3D hackers.

Axis uses OpenGL on SGI and Win 95/NT, and Mesa on the remaining platforms. The 3dfx accelerated version utilizes the Mesa Voodoo libraries. The Linux version currently has the best coloring/shading; the different OpenGL implementations have quirks that we haven't sorted out yet.

The rendering engine uses a simple stack machine interpreter, and processes a language that has similarities to Lisp, Forth, and Adobe's PostScript. The interpreter is multi-threaded, so objects in the 3D environment can have private namespaces. We are working on a programming manual for the language.

It is also network-ready; you can talk directly to the rendering engine with a TCP/IP connection. The distribution includes source code for an example TclTk program which utilizes the network connection (this is the tool we used to position models within the 3D environment). We will be releasing more complex modelers shortly.

The rendering engine and language interpreter will be the base for our multi-user shared environment application, which we plan to release near the end of July. Environments, and information about positions of other users, will be downloaded via TCP/IP; if you choose to customize your avatar, code for that can be uploaded.

Enjoy, and let me know if you have questions.

Patrick H. Madden
phm@webvision.com
pickle@cs.ucla.edu
or
phm@ikm.com when we get our mail server sorted out.....

## WSCG '98 International Conference and Exhibition Call for Papers and Participation Deadline for papers September 30,1998 The Sixth International Conference in Central Europe on Computer Graphics and Visualization 98 in cooperation with IFIP working group 5.10 on Computer Graphics and Virtual Worlds will be held in February 9 - 13, 1998 in Plzen at the University of West Bohemia close to PRAGUE, the capital of Czech Republic Conference Chairs Nadia Magnenat Thalmann, MIRALab-CUI, Univ. of Geneva, Switzerland Vaclav Skala, Univ. of West Bohemia, Czech Republic The latest information is available at: http://wscg.zcu.cz or http://herakles.zcu.cz Full announcement in plain text is available.
## POV Texture Library This texture library has been updated and the URL has changed. This site is done by a non-Unix user, but the textures are platform inspecific.If you're looking for some interesting textures for your POV-Ray scenes take a look at http://www.informatik.tu-cottbus.de/ ~rs/povray/texlib/
## IRTC CD-ROM Due out soon! Chris Cason, who manages the server which supports the IRTC and POV-Ray Web sites. is getting ready to publish the IRTC CD-ROM. This CD contains the collection of images submitted to the IRTC over that last year, the IRTC's first year of existance (in its reincarnation that is). If you're interested in getting a copy of this CD, please check out the IRTC Web site for more information. All proceeds from the CD go to the maintenence and expansion of the Web server.
|  | ## EPSON Scanner Driver EPSCAN is a scanner driver for EPSON ES-1200C/GT-9000 scanners. It includes a driver and a nice X frontend. It allows previewing, and selecting a region of an image to be scanned, as well as changing scanner settings. It only supports scanners attached to a SCSI port, not to the parallel port. The driver should support any of the ES-{300-800}C / GT-{1000-6500}. EPSCAN is available from: ftp://sunsite.unc.edu/pub/ Linux/Incoming/epscan-0.1.tar.gz and an rpm version to ftp://ftp.redhat.com/pub/ Incoming/epscan-0.1-1.src.rpm ftp://ftp.redhat.com/pub/ Incoming/epscan-0.1-1.i386.rpm The rpm version will probably be moved, if it hasn't already, to ftp://ftp.redhat.com/pub/ contrib/epscan-0.1-1.src.rpm ftp://ftp.redhat.com/pub/ contrib/epscan-0.1-1.i386.rpm The sunsite version will probably be moved to ftp://sunsite.unc.edu/pub/ Linux/apps/graphics/scanners/epscan-0.1.tar.gz Adam P. Jenkins ajenkins@cs.umass.edu Requirements: Linux 2.x XFree3.x Qt library version >= 1.1 libtiff version >= 3.4 g++ version >= 2.7.2 You can get the Qt library from http://www.troll.no. EPSCAN may work with older versions of Linux, XFree, and g++; this is just what it was developed with.
Has anyone tried out ELECTRO-GIG's product, 3DGO? The Graphics Muse wants to know! Its 37M and downloading across a 36.6 modem is painful at best. I'd love to try it, but I don't have the cash on hand for ordering it and having it shipped (I don't mind paying for it, but next months trip to SIGGRAPH plus some vacation time sort of sucked me dry for the time being). If you've used it let me know your thoughts. I'll be happy to pass any review on to my readers, with full credit to you of course!
## Iv2Pov/IV2Ray Cow House Productions is pleased to announce the release of Iv2POV. Iv2POV is a translator / converter for Inventor 2.0 / VRML 1.0 files to POVRAY, the popular raytracing program. Both source code and an Irix 5.3 executable are available (free!) at http://www.cowhouse.com/ Home/Converters/converters.html. Cow House is also pleased to present a new release of Iv2Ray, the Inventor (VRML 1.0) to Rayshade (a different popular raytracing program) converter / translator. Iv2Ray is also available as an Irix 5.3 binary and as C++ source code. While you are at www.cowhouse.com - feel free to take a look around, download some samples, and otherwise exerciseyour browser.

#### Did You Know?

...the growth of 3D modellers continues at a frightening pace. Another modeller was recently announced: GL-SPACE. You can find information on this new modeller at http://tularosa.eece.unm.edu/staff/greywolf/glspace/. It requires Tcl7.5/Tk4.1 and Mesa 1.2.8 or OpenGL. The interface is quite cool - one of the best I've seen yet. The cameras location is represented by - a camera! Really. Take a look at it.

...there is a very nifty morphing tool, called xmrm, available at http://www.cg.tuwien.ac.at/research/ca/mrm/index.html. I played with this a little and it has one of the most professional looking interfaces I've seen in awhile. Its relatively easy to use, at least if you follow the one example morph it provides.

...there is a Web site devoted to explaining how to make MPEG movies? Take a look at http://www.arc.umn.edu/ GVL/Software/mpeg.html to find out more.

#### Q and A

Q: I am quite new to POVRAY and would like to know where I can get an application which plays a series of *.tga files as an animation. I have created all the TGA files using POV. What can I use to play these files in sequence?
Merv Young.
AUSTRALIA.

A: Well, I don't know of any tools that can take a set of TGA files and directly turn them into an animation on Linux systems. I'm not that familiar with animations yet, but here is what I do know.

First, you have two types of animations you can create (with freely available tools) from a set of raster images: MPEG or an animated GIF. The latter requires the images to be in GIF format (GIF89a, actually). There are two tools for taking the GIF files and turning them into an animation: WhilrGIF and MultiGIF. Both are command line tools and both are fairly easy to use. I like MultiGIF a little more simply because it can create smaller animation using sprites (small images that can overlay the previous image). Understanding how to do this is a little tricky, but not that tough. WhirlGIF simply concatenates the set of GIFs together into an animated sequence. Playing an animated GIF can only be done by Web browsers, although I only know for certain that both Netscape and MSIE support this format. To my knowledge (someone correct me if I'm wrong) there are no "animated GIF players" for Linux.

MPEG is an animation format that I've just started to experiment with. There is only one command line tool that I'm aware of for creating the animations - mpeg_encode - but there are quite a few tools for viewing them (xanim, MpegTV, mpeg_play, etc). Creating the animation is done by setting up a text file with the configuration information needed by mpeg_encode. It then reads the configuration file, determines what sort of processing is to be done and takes the input files and creates the MPEG output file. The configuration can be fairly sophisticated, but I found the default template worked fairly well with only a few minor modifications. One of those modifications was to tell mpeg_encode what other tool to use to convert the input files, which were in TIFF format (rendered from BMRT), into a format that mpeg_encode could handle. Fortunately, mpeg_encode handles two fairly common formats: JPEG and PPM/PNM (it actually supports a couple of others, but these two will be readily recognizable to most users). I used the NetPBM tool tifftopnm. The TIFF files are converted on the fly by mpeg_encode as long as you tell it what converter to use.
There is another format called FLI which has an encoder. My understanding is that this format is slowly dying as MPEG gains popularity.

So now that you know what formats you need to put the animation in you might wonder how to get the TGA files into the formats you need. Thats a common question when dealing with both 2D and 3D images, in both animated and static formats. The answer: get either the NetPBM tools. ImageMagick, or ImageAlchemy (the latter being a more sophisticated commercial product). Any of these are valuable tools for your arsenal of image processing since they all perform the often needed task of converting from one format to another. NetPBM is what I currently use, although I don't believe it has a tool for converting JPEG images to other formats (there is an add-on package for NetPBM that handles this, but I don't think the NetPBM package itself has JPEG conversion tools - I could be wrong, its been awhile since I downloaded the package).

So, to summarize how to get your TGA files into an animation:

- Deterine which animation format you want to create.
- Determine what format the input files need to be in (GIF, JPEG or PNM).
- Be sure you have a tool for converting the TGA files to the input format - this may be a two step process and it may be possible to get the animation creation software to handle the conversion for you (such as with mpeg_encode).
- Get the encoding tools - mpeg_encode, WhirlGIF or MultiGIF.

## Is VRML ready for PrimeTime?

Some time back I had a reader send me email asking my thoughts on VRML. Below is the response I sent. After rereading it I have to say I still agree with it, although I reserve the right to change my mind after my trip to SIGGRAPH next month.

Reagen Ward wrote:
I come from the world of PHIGS for visualization, and thus can't stand VRML as a supposed data format. I'd love to hear your opinions on why it's not ready for personal use.

Originally I had objected to it due to bandwidth issues. I've learned since then that this may not be as big a limitation as I once thought since VRML provides a language which can be passed between client and server and doesn't (to my knowledge - which admittedly is still somewhat limited) require the actual images to be passed. PHIGS could probably be done this way too, but PHIGS needs a "PHIGS for Dummies" layer slapped on top to make it a little more user friendly.

However, the real limitation right now is processing power. Even if you pass only descriptions of the objects to render, the end system still has to be fast enough to render them from the point of view of the user. This is very CPU intensive. The average user doesn't have this kind of processing power (have you seen the new WebTV boxes? They are even slower and
dumber than the average 2 year old PC). This processing could be moved off CPU into some adapter card (maybe a VRML-ready display card), but such technology isn't available yet so its cost would still be (for some time) out of the reach of the average home.

Now its not unlikely to see VRML in some environs: kiosks in stores or malls (real ones, not Internet Malls) come to mind or any kind of public facility that provides information to users to be browsed at their own pace. These places will have limited point-of-view (like point-of-sale) locations on a local network so bandwidth is not a problem, nor is server capacity (its known pretty much ahead of time how much activity they're likely to have). The point-of-view boxes can be as powerful as the mall can afford. VRML provides a reasonable return-on-investment for these situations.

But the big money, and money (income, that is) is what drives acceptance, only comes when you can move the technology into the home. Thats what WebTV's are all about - computers for the common man at toaster prices. VRML requires too much processing for the average home, so its not likely to be a big technology for at least 2-5 years. It depends on if Intel/Sun/HP/etc can find a way to make money producing VRML-toasters.

Hows that?

##
## Image Alchemy One of the most common tasks graphic artists will face is converting stock images from CDs and other resources from their original format to one that can be used by their particular software or medium (such as for use on the Web). There are actually a plethora of tools for doing this conversion. xv will convert between a limited set of formats, but does handle most of the most common formats. The NetPBM tools handle a huge number of formats using a very large set of command-line programs. And ImageMagick has both command line and X-based interfaces for converting images. Each of these has advantages and users will want to play with each to find one that suits their needs. Another solution for image conversion and manipulation comes from Handmade Software in their Image Alchemy package. This is a commercial package that features support for over 60 different image file formats using a command line interface. A graphical interface is available for Sun systems using OpenLook and there may now be a Motif version as well, however these do not appear to be available for Linux yet. Getting the software requires that you simply download the Linux binary package from the download page of Handmade's Web site. There is a demo package available for free, but the retail version requires a username and password that can be obtained from their sales department. The package I have, which I got from Hap Nesbitt at Handmade Software, contains two binaries: alchemy and alchfont. The former is the graphics conversion package. The latter is a font manager, although I'm not really clear on how to use it. The documentation, 330+ pages in a PDF file, didn't contain any references to it. Since I wasn't expecting this tool I didn't spend any time looking for info on it at the Handmade Software Web site. The manual is available for download from their Web site. Its quite large (something you'd expect from commercial software and something that is seriously lacking in many freeware packages) but it covers all the versions of the software, including 2 chapters (out of 8) and 1 appendix (out of 11) on the DOS/Windows Graphical interface. Along with the manual you can get runtime help by using the -help command line option. The runtime help is broken into several categories, each with its own command line option. The basic usage takes the following form: alchemy inputfile [outputfile] [outputpath] [options] The input file can be in any of the supported formats listed in the manual. The output file can be any name. By default the converted file will be written to a file with the same filename as the input file but with the appropriate suffix. For example, newfile.tga would become newfile.gif. Outputpath is useful when you want to convert a series of images. Options can be any of a large number of conversion options, many of which are file format specific. The only required option is the one which specifies which file format the output file should be in. Text files, what Image Alchemy refers to as response files, with options can be used by specifying the file name preceeded with an '@' sign, such as alchemy @scale myimagein.tif myimagein.gif Basically, you can convert one or more images, to files in the local directory or some other directory, using the command line directly or through the use of the text files. Unlike NetPBM the images don't have to be converted to an interim format before the final image is produced. NetPBM used the interim format to do its image manipulation, such as scaling or quantizing the colors in the image. Image Alchemy can do this in one step using various options. Speaking of options, the Image Alchemy manual breaks the available options into 4 categories: General Conversion Color and Palette Scaling and Filtering -Top of next column- |  |
More Musings... -- ImageMagic
General options include items such as usage, statistics and memory features. Conversion options specify the output file types and any related options. For example, -g is the option for converting to the GIF format. This option has an additional numeric argument, 0 or 1, to specify which version of the GIF format to use - GIF87A or GIF89A respectively. Color and Palette options cover such things as alpha channels, true color options, dithering and gamma correction. Scaling options allow the resizing of the input image and along with the Filters provide for convolution, flipping, positioning and aspect modifications. All of the options are covered in detail by the manual and summaries are available through the builtin help option (-help). When evaluating image conversion utilties the artist will want to compare the quality and sizes of the images. On my 24-bit display the quality of the sample JPEG image provided with Image Alchemy (a photo of the Golden Gate Bridge) didn't change perceptibly when converted to GIF, Targa (TGA) or TIFF formats. The same image was converted using xv and NetPBM to these same formats and also showed almost not visible differences. The following table shows the file sizes for each:
| GIF | TGA | TIFF
alchemy | 192360 | 924059 | 769700
xv | 142784 | 921618 | 772046
NetPBM | 146100 | 921618 | -
ImageMagick |  |  |
Note that my version of NetPBM does not include the JPEG conversion utilities so the TIFF image converted by alchemy was used as the input image for NetPBM's tools. As you can see, the file sizes were very similar for TGA. Image Alchemy produced a significantly larger version for the GIF format and a slightly smaller version of the TIFF. Based on this a user might assume xv or NetPBM might be better suited for their needs. In many cases this is true, especially if you are only doing a personal web page or perhaps creating simple greeting cards. For professional work alchemy provides a wider range of tools and supported formats than xv and NetPBM, and does so with a single command line program. Both xv and alchemy provide significant documentation (you can get xv's by registering your copy and paying a little extra for the manual). NetPBM provides man pages but these can be difficult to print and its not always easy to determine which tool fits which format. Only Image Alchemy offers commercial support and with continued development at published intervals. For commercial operations this can be of key importance. The moral here is to spend a little time examining your image conversion needs before investing time in any one particular tool. Image processing is provided by all of these, but aside from scaling and perhaps color palette operations you may find the GIMP a better tool for interactive editing of images. If you need the convenience of command line oriented operation for batch processing, along with commercial support, then Image Alchemy may be the tool for you.

The following links are just starting points for finding more information about computer graphics and multimedia in general for Linux systems. If you have some application specific information for me, I'll add them to my other pages or you can contact the maintainer of some other web site. I'll consider adding other general references here, but application or site specific information needs to go into one of the following general references and not listed here.

Linux Graphics mini-Howto Unix Graphics Utilities Linux Multimedia Page Some of the Mailing Lists and Newsgroups I keep an eye on and where I get alot of the information in this column: The Gimp User and Gimp Developer Mailing Lists. The IRTC-L discussion list comp.graphics.rendering.raytracing comp.graphics.rendering.renderman comp.graphics.api.opengl comp.os.linux.announce |

## Future Directions

Next month:

No Muse next month (September). I'll be at SIGGRAPH and otherwise busy throughout August and just won't have time for it. But I'll be back in October, probably with lots of goodies from SIGGRAPH (or at least I hope I am!).

Let me know what you'd like to hear about!

##### Copyright © 1997, Michael J. Hammel
Published in Issue 20 of the Linux Gazette, August 1997