Super Simple Texture Compression

S2TC will work anywhere a developer would use S3TC. For the end-user, S2TC works on hardware and platform combinations that are not compatible with S3TC.

There are some important differences. S2TC is an "offline" compression format while S3TC is "online". That means S3TC textures are actually stored on the video card. S3TC converts a 4x4 pixel block into a binary number. S2TC uses a 2x2 block. As for the S3TC patent, it only covers one method of compression which is not optimal. Most developers use a different compression method. This does not violate the patent and does not require a license. Hence, no barriers whatsoever for a developer to use S3TC unless they would rather pay for a less optimal solution. But the decompression is fully legally locked to the S3TC patent. Hence, barriers for the end-user if their software or hardware does not support S3TC decompression (netbooks for example). Finally, to state it implicitly, S2TC decompression only decompresses S2TC textures, it does not decompress S3TC textures.
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