BLP2PNG
From Source Peek Wiki
About
This tool is used for converting bi-directionally between BLP and PNG images. The tool fully supports alpha channels and can be used as a drag-and-drop converter or from the command line. It can also convert your existing TGA files to PNG.
BLP2PNG will convert the file based on the original type:
BLP are converted to PNG BMP are converted to PNG TGA are converted to PNG PNG are converted to BLP
Why PNG when everybody uses TGA?
PNG is a modern image format and is better supported by more tools and even most web browsers. Support for PNG in Photoshop is much better than it is for TGA, which makes editing high-quality textures for addons a lot easier. If you prefer working in TGA then by all means keep using the many existing tools for converting those images. I use this tool for converting WoW's artwork to PNG so I can use it as a reference for my own artwork. I also use this tool to convert my own artwork to BLP files for use in my addons, including GroupCalendar and Outfitter. If you prefer PNG like I do, this tool will make things much easier for you.
