TGA is a long-used raster graphic format. It was developed by Truevision Inc. (now Pinnacle Systems) back in 1984. It was initially used by the developer only for its own graphic adapters, but gradually gained popularity (primarily in the field of video processing and animation). Widely used in computer games, where it is used to store textures (including 3D video games). The name of the format comes from Targa Graphic. TGA files may partially contain image transparency information. They can become the main one for creating GIFs.
J2K is a raster image category file format. It is a compressed bitmap using wave compression instead of DCT compression, which is used by standard .JPEG images. The format supports 16-bit color, alpha transparency and lossless compression. The file type is JPEG 2000 Image. The J2K file format was developed by the Joint Photographic Experts Group (JPEG). J2K is an update to the JPEG format that includes original features. Say alpha channel support and lossless compression. J2K is a segment of a large package of updated JPEG extensions. They gained fame as JPEG2000. Such as J2C, JPX, JPM or JP2. The lion's share of such formats are combined with the main programs so that you can view images. However, JPEG is particularly popular. For those who specialize in photography, it is important that they have the opportunity to reduce the file size, while saving it on disk with the same frame size and at the same high visual quality. How to get out of this situation? You can, for example, store images in JPEG2000 format with the file extension jp2 or j2k. The compression algorithm and the format itself have been known for over 10 years. Nevertheless, there is no need to talk about its widespread use. That's because his "big brother" JPEG is firmly holding on to its position.