The death of .png?
A couple of days ago the much maligned LZW compression patent expired in the US. Y'know, the compression routine behind the .gif (Graphic Interchange Format) file format. Previously, anyone wanting to produce software that had the capability to produce .gif images had to pay a royalty to the patent holder, Unisys. This kinda put the kybosh on using .gif images in open source software as I found out much to my dismay when using the GD library for PHP a while back.
The patent free alternative to .gif, .png (Portable Network Graphic - pronounced 'ping') was a great idea that has sadly never had the support in browsers it deserved. It comes in two flavours, 8 and 24 bit. 8 bit .png most closely resembles the .gif format, with the ability to have transparent pixels but lacked support for animation (for that you'd use .mng - pronounced, well, you get the idea). The main strength of 8 bit .png is that it tends to produce smaller file sizes than an identical .gif. 24 bit .png is a much more interesting animal. With .gif and 8 bit .png a transparent pixel is either 100% transparent or opaque. Problem here is much jaggedy edges when layering a transparent .gif or 8 bit .png containing a curve or anti aliased text over another image. 24 bit .png, on the other hand, supports multiple alpha channels - or variable transparency of pixels. 24 bit .png is also a lossless format - say bye bye to those nasty .jpg compression artifact. It also has much better gamma settings than either .gif or .jpg which means colour representation across browsers and operating systems is much better - anyone who has created a .jpg on a pc and then looked at it on a Mac will know why this is a good thing. All in all it's a bit of a jack of all trades type of image format that could, and should, in theory replace .gif and .jpg as the file format of choice for graphics on the world wide web.
So why aren't we all using it? Originally take up was slow due to the fact that a plugin was required to view the images, although all major browsers from version 4-5 onwards include at least rudimentary support. Sadly the blame lies firmly in Redmond, Washington. Although 8 bit .png displays correctly in Internet Explorer, 24 bit .pngs with alpha shaded pixels do not. Since IE commands such a large market share it is pointless relying on alpha shaded .pngs as part of your site design.
So where does the expiry of the LZW patent leave .png? Tough question. Support for .png has been growing for a number of years, but mainly as an alternative to avoiding the Unisys tax. Chances are .png will now sink into obscurity when faced with wide spread acceptance of inferior alternatives and inconsistent support that destroy it's chances of gaining mainstream use and acceptance. Which is a great shame due to the unique strengths of the format.