TGA stands for Truevision Advanced Raster Graphics Adapter (TARGA)
TARGA is a raster graphics file format created by Truevision Inc which is now part of Avid Technology. It was used on early graphics cards on PC computers. The extension is .tga for files in this format. The format can store image data with 8, 15, 16, and 24 bits of precision per pixel – A 32 bit version is also supported the maximum 24 bits of RGB and an extra 8-bit alpha, (transparency) channel. This image is uncompressed or compressed using RLE encoding.