It's me again :D.

Most previews seem broken, they only display a monochrome picture. I've only tested actually converting DXT1 to ATI2, which seems to have worked (ie, the texture displays fine in IE, it's not monochrome).

Also, just realized DXT5/DXT1 to PNG/BMP results in a compressed file a few dozen bytes big. That is quite the compression. Do you store the rest of the data in quantum space ?^^

Test files : Out.zip