Thumbplug TGA is a windows explorer tga addon.
The TGA(Targa) format supports many formats but most of them are pretty rare. For example, TGA files can have their images stored in any direction, right to left, bottom to top, top to bottom, left to right. They can also support 15 and 16 bit pixels. But, in my personal experience, I’ve never seen a TGA file stored any way other than bottom to top left to right. I’ve also never personally used a 16 bit TGA file nor have I used or seen any of the other options. Therefore, there is no support for those other formats in this plug in.