DXT Compression

Lithtech 2.1 / 2.2

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Post by Coty » Fri Oct 28, 2005 11:59 am

Taken from an Unreal Wiki:

Which DXT Compression to Use?
Obviously, there are some trade-offs between the different formats which make them better or worse for different types of images. Some general rules of thumb for good use of DXT textures are as follows:

If your image has no alpha, use DXT1 compression. Using DXT3/5 will double your image size over DXT1 and not gain anything.

If your image has 1-bit (on or off) alpha information, use either DXT3 or DXT5 (which one doesn't matter, they'll give the same results).

If your image has smooth gradations of alpha (fading in/out slowly), DXT5 is almost certainly your best bet, as it will give you the most accurate transparency representation.

If your image has sharp transitions between multiple alpha levels (one pixel is 100%, the next one is 50%, and another neighbor is 12%), DXT3 is probably your best bet. You may want to carefully compare the alpha results in DXT3 and DXT5 compression, however, to make sure.

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