...
- PNG - standard high quality lossless compressed image format
- GIF - can be animated, but otherwise a lossy compressed image format
- JPG - JPEG file a lossy photo-like image file, but much lower size then PNG or TGA/DDS
- WBM - WebM files, technically video so can be animated, but won't play sound.
DDS and TGA can be loaded as normal. DDS and PLT are not supported however (if a DDS version of a TGA file exists, for instance, it just won't ever find the DDS version and loads the TGA one instead).
The order of priority for same-named files are: JPG > TGA > PNG > GIF > WBM