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Using animated PNG files
by Mike Slocombe
Q: I'm updating my site and would like some timeline animated pics flying about the place. Apparently .png's will support a clean transparency through an alpha channel, as opposed to the blocky .gif 'transparent colour' solution.
What's the latest on png support in the most used browsers out there?
The PNG image format was designed to be a replacement for the GIF format, due to both copyright and design problems with GIF. Despite the specification being released four years ago, all the latest versions of popular browsers (IE/Netscape/Opera/Mozilla) only offer incomplete PNG support which is sadly bedeviled with a depressing catalogue of browser bugs, quirks, glitches and inconsistencies.
There's far too many of them to list here, but you can catch up on developments here: www.libpng.org/pub/png/
Some designers have got so fed up waiting for Microsoft to properly support PNG, they've launched an online petition: www.petitiononline.com/msiepng/petition.html
Practically, I'd carefully check your requirements against documented browser bugs and consider using GIFs for now. Another alternative would be to use Flash to create your animations
More info on the PNG format: www.w3.org/Graphics/PNG/