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Common Problems Creating GIF Animations

1. Large space below and to the right of the GIF; GPF on animation.

GIF Logical Screen Header is too big or too small. This occurs with GIF Construction Set. Version 1.0L eliminates this error. The first block of the GIF is the LOGICAL SCREEN HEADER, normally set to 640x480. These values define how large your GIF is onscreen. The sizes of the actual images donít determine how big the overall GIF is. Set the LOGICAL SCREEN HEADER large enough to include any of the images in the animation. Too small a Logical Screen will cause a GPF, too big leaves a border below and too the right.

Looping animation repaint on screen when they restart.

Interlacing should not be used in animated GIFs. Turn interlacing off of all images.

Transparent animations leave trails or arenít transparent at all.

Each and every image must have a CONTROL BLOCK before it with Transparency turned on and REMOVAL/DISPOSAL BY BACKGROUND set.

4. Timing or transparency doesnít take place at the correct points in the animations.

Control blocks will only affect a single image which immediately follows it. When viewing inside GIF Construction Set control blocks are treated incorrectly. Each image must have a Control Block placed BEFORE it. A Control Blockís features affect the SINGLE image that follows it. Timing delays are executed from the point after the images is displayed.

Animations get stuck, don't loop, or donít animate at all.

After installing Netscape delete your CACHE directory. The cache is a vital component in animations. Corruptions due to beta upgrades can cause animations to hang. Netscape 2, 3, and 4 betashave done this. Maintaining multiple versions of Netscape often cause this since they all use one cache folder, the one pointed to by \WINDOWS\NETSCAPE.INI.

This can also be caused by backslashes(\) being used instead of slashes(/) in an URL. The other known cause is the use of a <BASE HREF="/"> tag. If this tag doesn't include HTTP:// the entire page will be affected.

Animated GIF Backgrounds, User Input, and Previous Image Removal/Disposal.

ANimated GIF backgrounds are supported by Netscape 4 and IE4 browsers or later. Browsers prior to 4th generation and other brand browsers have not added support for this. It must be used sparingly as it has dizzying effects, confuses the page, and makes text on the page largely unreadible. I suggested if you use this, it be any incredible mild animation, be on a splash page where the user does not read anything, or use tables with background color fills to display contents of the page.

No one has announced any planned support for User Input. Previous Image Removal appears to be supported in the Internet Explorer 3 and later.

Timing Delays too slow, too fast, not at all

Early versions of GIF Construction set said timed delays were in seconds. This was wrong. Timed delays are in 100ths of a second. A value of 100 equals one second. Navigator has a minimum overhead time which can be as much as 33/100 of a second. This means that slow Pcs that makes a request for a times delay will see a minimum of a 33/100 of a second between images. Some on Windows and MAC report a minimum of 10/100ths of a second between images. I believe this depends upon processor speeds.

Looping and stopping problems.

Netscape 2.0 only does infinite loops and animations can be stopped by the ESC/STOP buttons. Early 3.0 betas wonít STOP. 3.0beta4 returned the ability to stop animations. All 3.0 versions support the loop count. MS Explorer 2 for Mac doesít loop animations. Explorer 3.0 betas support loops, For all of them, DISK CACHE must be enabled for loops to execute. If animation is too big to fit in disk cache it will not loop.

Animations are slow

GIFBuilder has an automatic feature that eliminates the major cause of this problem. Many animators repaint the entire frame over and over, even if very little changes. GIF89a animation allows you to animate small portions of the GIF reducing file size significantly. Smaller palettes also reduce size. GIF can have any number of color from 2 to 256. Check out the Conservation page on How To make Smaller GIFs

When I open the file directly into the browser...

This is part of the "It hurts when I do this. So don't do it" Browsers are not meant as image viewers. The code is not written to display nicely when viewing a raw image file without HTML code. Netscape will flash a black screen at the begining and at the first loop. When you place the images on a page that won't happen anymore.

Graphic HTML tag not working.

Animated GIFs have only been supported in <IMG> tags, <FIG> support has not shown up. Netscape 2.0 or later, MS Explorer 3.0, and Opera 2.0 all support GIF animations. Other browsers will not animate. Also make sure you have uploaded (through FTP for most) the GIF files as a binary file to your Web service. You must upload the file properly before it will be viewable in an <IMG> tag

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Copyright 1996,1997 Royal E. Frazier Jr. Last Updated: March 1997