120 lines
4.7 KiB
HTML
120 lines
4.7 KiB
HTML
<BODY>
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<HEAD>
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<TITLE>
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Graphics Muse
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</TITLE>
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</HEAD>
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<BODY text="#000000" bgcolor="#ffffff"
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vlink="#fa3333" alink="#33CC33" link="#0000FA">
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<!-- =============================================================
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This Page Designed by Michael J. Hammel.
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Permission to use all graphics and other content for private,
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non-commercial use is granted provided you give me (or the
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original authors/artists) credit for the work.
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CD-ROM distributors and commercial ventures interested in
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providing the Graphics Muse for a fee must contact me,
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Michael J. Hammel (mjhammel@csn.net), for permission.
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============================================================= !-->
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<A NAME="musings">
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<table>
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<tr>
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<td>
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<H2>More...</H2>
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<BR clear=both>
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<IMG SRC=../gx/hammel/musings.gif ALT="Musings" ALIGN="left"
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HSPACE="0" VSPACE="0" WIDTH="247" HEIGHT="52">
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</td>
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</table>
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</A>
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<BR clear=both>
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<table>
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<tr><td>
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<UL>
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<LI><A HREF="#gif-animations">Creating GIF Animations</A>
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</UL></td>
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</table>
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<IMG SRC=../gx/hammel/cleardot.gif ALT="indent" ALIGN="left"
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VSPACE="35" WIDTH="1" HEIGHT="1">
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<BR clear=both>
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<P>
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<A NAME="gif-animations">
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<H4>Creating GIF Animations</H4>
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</A>
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<IMG SRC=../gx/hammel/cleardot.gif ALT="indent" ALIGN="left"
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HSPACE="5" WIDTH="1" HEIGHT="1">
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Recently, while working on a text on Unix web servers, I was tasked with
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writing about multimedia applications. During my research on this subject
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I discovered a little known fact about the GIF image file format: it supports
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multiple images in a single file which can be used to create animations.
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Creating GIF images is fairly simple. There a number of tools available
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for Linux systems that can either create new GIF images or convert image
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files in other formats to the GIF format. Tools such as the <I>Gimp</I> or
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<I>XPaint</I>
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can be used to create images while <I>xv</I> or the <I>NetPBM</I>
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tools can be used to convert images from other formats.
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<BR>
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<IMG SRC=../gx/hammel/cleardot.gif ALT="indent" ALIGN="left"
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HSPACE="5" WIDTH="1" HEIGHT="1">
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In order to create a GIF animation you must first create a series of GIF
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images. These images make up the frames of the animation, much like cell
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animations make up a cartoon (although there is no reason why your GIF
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files can't be converted from 3D images such as those created with POV-Ray or
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BMRT). The animation only plays as fast the the host machines ability to
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read, decode and display the individual frames. On older 486 systems this
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might be a problem so its wise to keep your images small. For GIF images
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this means keeping the dimensions (height and width) of the animation small.
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You should also consider how jumpy you want the animation to be. Small
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amounts of movement of objects from frame to frame will reduce the
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jumpiness of the overall animation, but it also can significantly increase
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the overall size of the GIF file. Since Netscape (the only browser that
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I know of that currently supports this type of animation) tries to load the
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entire GIF file before it begins playing the animation it would be wise to
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consider keeping the file size small.
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<BR>
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<IMG SRC=../gx/hammel/cleardot.gif ALT="indent" ALIGN="left"
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HSPACE="5" WIDTH="1" HEIGHT="1">
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Once you have the individual frames created, you'll need to put them all
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into a single GIF file. You can use a nifty little tool called
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<A HREF="http://www.msg.net/utility/whirlgif/">
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WhirlGIF</A>
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to do this. WhirlGIF is a command line tool (no GUI) that concatenates the
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series of GIF images into a single GIF image and configures the GIF header
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so that Netscape will know how to play the animation. The GIF header
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allows for a number of options, including some that are Netscape specific
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(Netscape didn't create their own format - the GIF format allows for
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application specific extensions). You can provide the number of times to
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loop the animation and the delay time to use between frames (which can be
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used to slow down and animation if so desired).
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<BR>
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<IMG SRC=../gx/hammel/cleardot.gif ALT="indent" ALIGN="left"
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HSPACE="5" WIDTH="1" HEIGHT="1">
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There is a terrific page devoted to GIF animations at
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<A HREF="http://members.aol.com/royalef/gifanim.htm">
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http://members.aol.com/royalef/gifanim.htm</A>. This page is not Linux (or
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Unix) specific, but it does include pointers to WhirlGIF and the
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information in a number of the pages there are very applicable to creating
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GIF animations on Linux systems.
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<BR>
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<IMG SRC=../gx/hammel/cleardot.gif ALT="indent" ALIGN="left"
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VSPACE="35" WIDTH="1" HEIGHT="1">
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<BR clear=both>
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<!--===================================================================-->
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<P> <hr> <P>
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<center><H5>Copyright © 1996, Michael J. Hammel </H5></center>
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<center> <H5>Published in Issue 12 of the Linux Gazette</H5></center>
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<P> <hr> <P>
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</BODY>
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</HTML>
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