GIF89a Animation Bugs in Software

[Previous]
[Find]
[Next]

Royal Frazier's

- MIRROR sites: closer, faster, non-English -

[Home] [Introduction] [Find] [UrlMinder] [Viewing] [Software] [How to make GIF Animations] [HTML] [Smaller GIFs] [Common Problems] [GIF Bugs] [Technical] [Gallery] [About]

If you have a few minutes, please fill out the Visitor Survey. It will help in making this site better.

This page is a collection of bugs, anomalies, and strange behaviors that are found throughout the GIF89a documents. It should help to identify problems that you can do nothing about. Hopefully they will one day be as squashable as good ol' Milque.

On the MAC version. A page with an undefined Background will null the use of REMOVAL by BACKGROUND in the control box.
On the Windows Version, The last few frames of an animation will play slower than the rest. This is true even when animations loop.
When linking or returning to a Framed page from a page with animations you may GPF. The error will occur when the animation on the starting page is active. Hitting STOP and ending the play of the GIF will avoid the bug. This is reliably seen when the target "_top" is used in a link. This bug is fixed in the commercial release of 2.0, but not in any of the betas.
Corel has an annoying bug when exporting: a white line on the bottom and/or right edge of the bitmap when you don't have an outline width set. This can be solved if you add an outline to the object for most cases.
Netscape doesn't support Remove by Previous Image. Previous image should restore the image back to the way it was before the image was painted on.
a bug in GIF Construction Set for Windows. The positioning of the images inside the GIF file is off by one pixel down and one pixel right. If you set the position at 0,0, GIFCon will position it at 1,1. Netscape does NOT make this mistake.
Inserting a image larger than the screen size will cause a GPF in earlier version of Netscape. GIFAnim software is now being written to not allow this to happen.
DO NOT HIT [ENTER]! in dialog boxes in GIFCon before version 1.0F. That CANCELS in version 1.0c! Click on the OK button with the mouse.
The USE AS IS option when inserting an image in GIFCon (before 1.0F) causes a GPF in GIFCon when you go to save.
When you use MERGE in GIFCon, local palettes are set for all merged images, but attempting to edit a Control block gets the error message "No global color table, and no subsequent images found." This error is erroneous, as it happens even when there is a global color palette.
User Input flag in GIFs is unsupported in Netscape Navigator.not supported by any browser
Netscape 2.0 before beta3 ignores timing delays.
Netscape 2.0 beta3 hangs on the first frame of a time delayed GIF
Netscape 2.0 beta4 through final for Windows contains a bug that prevents the GIF from playing faster than 34/100ths of a second between images.
Netscape 2.0 beta4 through final for Windows contains a bug that causes the last few frame of the animation to play slower.
Netscape 2.0 beta 5 and 6 will GPF on going to a "_top" targeted page from a framed page with running animations. You can avoid the error by stopping all animation, or by getting the final version which fixed this.
Netscape users saw a lot of GPFs when closing Netscape, this is solved with the final version.
There is a bug in Transparency with frames. My Link Cruiser page often displays the white background of the logo, rather than transparently displaying the background JPeG image. This only occurs in this framed instance. It is a problem in beta6.
Remove by Background in a Control Block paints the background of the Netscape browser over the image's area. This is normally gray. It is set in the Navigator Menu under, OPTIONS, GENERAL PREFERENCES, COLORS.
Remove by Background in a Control Block will paint your HTML-defined BACKGROUND or BGCOLOR if ,before the first image, comes a CONTROL block with transparency turned on (any color-doesn't matter.) Then the HTML set background GIF/color will be painted over the image's removal area.
Netscape 2.0Betas also have a major bug with printing. You can't in betas 4 and 5. Continuous animations causes the printing process to go into loops that it never came out of. Beta 6 solved this.
Framed pages always come up without any images, even though you had the Auto Load Images option checked. I always had to activate each image icon separately by clicking on it. The answer to this is that for some reason Netscape requires that checked Auto Load images option to be Saved and Netscape exited and restarted in order for the Auto Load Images function to work within frames. (Cache may or may not need to be cleared first also.) I generally run Netscape with the Auto Load Image option unchecked and just check it temporarily if I need it. Doing this apparently won't work for frames. (Alden Bliss)
Netscape Gold 3.0beta6 & 7: Editing a remote page that contains multiple animated .GIF file or form elements may cause the application to crash if you select Cancel at the Save dialog box.
Netscape 3.0beta7 for:MAC ONLY: Some, but not all GIF images (usually black and white) will not appear on printouts.
Netscape 3.0 & 3.01: Severer Printing pages with Animations in Netscape 3.0 & 3.01 for Windows/16-bit results in broken images and garbage on pages. Pieces of page end up upside down.
Netscape 2 & 3: If you are running in 256 color mode and have a Windows background (wallpaper) image present, minimizing then restoring Netscape, might cause images and the Netscape logo to appear in strange colors. Workarounds: 1) Open a new Netscape window (then close it if you wish). 2) Remove the Windows background image. (this is true in 2.0 and 3.0)
Animations stop when background music playing. This may be due to processor overload.
When animations are view directly in Netscape (by VIEW in right-click menu or by FILE, OPEN FILE) in 256-color mode the screen flasheses black when it loads and when it loops. This will not occur when you place the image in an HTML page but is also true for any page with one GIF image and no text. Netscape reports this happens when a custom colormap is installed. I think this may mean anything other than Netscape 216-color palette.
Animations play too fast in Netscape 3. Especially true when viewing hard-disk copies. First loop executes without any time delays.
Remove by Background not supported by Internet Explorer. They do support Remove by Previous Netscape supported the opposite. I'm sure this is purely coincidental.

(Go to the TOP of PAGE for MENUS)

LinkExchange Member

Last Updated: May 1997