Slashdot Mirror
GIF Slips Away From Unisys; Your Move, IBM
Twenty years ago, Terry Welch's improvement on Lempel-Ziv compression appeared in IEEE Computer magazine. The authors of unix 'compress' and the GIF standard incorporated that algorithm without realizing it was patent-pending. When the submarine patent surfaced ten years later, its new owner Unisys intimidated developers and web authors into moving away from GIFs, inspiring the creation of a better standard, though sadly still a less popular one. Today, July 7, 2004, Unisys's last LZW patent (in Canada) expires, leaving GIF once again free... almost. See, there's the small matter of IBM's patent, granted on the same algorithm, which is valid for another two years. That still has a chilling effect on GIF development, though the consensus seems to be that IBM would lose any court action it tried to bring. So how about it, IBM? You've got nothing to lose! Want to make a lot of geeks happy and release that final patent into the public domain?
I'm not sure on the merits of the GIF format after all these years, the only thing it brings to the web expierence is flashing adverts, PNG provides full alpha-transparency which is really required for the future of web design.
Because GIF is used MUCH more, so people writing software that make use of images in general (browsers, image editors, etc.) have to deal with this patented algorithm, or risk losing users because their software doesn't support one of the most widely used formats.
"The best laid plans of mice and men gang oft agley..." - ROBERT BURNS
It's hard to do away with GIF because GIF's are animated. PNG's are not. There's the MNG standard, which is basically an animated PNG, but it isn't widely supported yet.
You can't make animations with PNG files....
Sure you can, only the result is called MNG.
Belief is the currency of delusion.
The original Welch paper is pretty readable:
Terry A. Welch, "A Technique for High Performance Data Compression", IEEE Computer, Vol. 17, No. 6, 1984, pp. 8-19.
If you don't want to go to a library and look that up, then Google will find you about 12000 hits on "Welch LZW", and the first few all seem to be exactly what you want.
Actually that patent is being used in IBM's (second amended) counterclaims in the SCO v IBM case.
JeR
GIF is pronounced JIF.
.GIF files are pronounced JIF
Bob Berry, the developer of CompuShow for CompuServe (remember them - the people that invented the GIF format?) included with it an animated GIF89 format file that had a picture of him. It had a speach bubble with him saying:
Oh, incidentally, it's pronounced "JIF"
A quick google later and I've found a web site which has this, and other evidence that
http://www.olsenhome.com/gif/
Thanks for playing
PNG transparency works just fine in Internet Explorer. It's just a pain in the ass.
This website will tell you how to turn it on. You can see it working on my website.
No idea why it's not on by default, but if it works...
Just to set the record straight:
When I led the process of drafting the PNG specification, GIF animation did not yet exist. Animation was not part of the original GIF specification. The GIF89a specification *did* offer a mechanism for including multiple images in a single file, and a very basic (but, in retrospect, effective) mechanism for replacing only a specified part of the preceding image. But whether this was supposed to be animation with a time component was never defined, and there was in fact no way to specify how long each frame was supposed to appear, probably because the real intent was to be able to compose a single final still image from many sections. Multiple image GIFs were a footnote to the GIF specification which hardly anybody used until Netscape stepped in.
Netscape's animated GIF format was a clever hack on top of this: they defined a new GIF chunk to specify the pause between frames.
Here's the kicker: Netscape was repeatedly invited to participate in the PNG design process. They had someone reading the list, I gather, but they never offered any suggestions or contributions. If they had, they would likely have been considered very seriously.
But instead, the first we heard of GIF animation was its public release in Netscape (2.0 beta, if I recall correctly). They could have contributed to the design of a PNG or MNG that did include animation and, by way of that compelling feature, would have been more likely to quickly replace GIF. But they didn't.
We (the PNG designers) did consider retrofitting animation into PNG when Netscape's animated GIF appeared. In fact, I lobbied for that at one point. Unfortunately we had already finalized the functional specification and there was no hope of reaching agreement on how to "jam in" the animation feature at the last minute on top of an otherwise pretty elegant image format.
Instead, the MNG group was formed to create a specification for a powerful lossless animation format. And they succeeded -- but MNG has yet to really catch fire, and animated vector formats like SWF and SVG are gradually replacing animated GIF anyway for most purposes. At the end of the day, lossless bitmap animation is a pretty bandwidth-intensive proposition.
Check out the Apostrophe open-source CMS: http://www.apostrophenow.com/