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.
JNG is a raster format. It has a close relationship with PNG. The JNG format uses exactly the same structure as PNG. It stores data in the main JPEG stream, is able to store the alpha channel stream in the form of PNG or JPEG, as well as information in the form of text. It also supports gamma and color correction. This image file format uses lossless compression similar to standard .JPEG files. The format was developed as a sub-format for .MNG objects. However, it is quite suitable as a separate raster image format. Some JNG files include an optional alpha channel for transparency. It does not support standard JPEG files. It is also possible to include auxiliary data sections, which may contain information about color space and comments. JNG is a format that is not very popular. Nevertheless, it has such a very good property as a large degree of lossy graphics compression. He also has an alpha channel. Color data is stored in JPEG format. For alpha, there is one of two storage options. It can be compressed using JPEG, like a grayscale picture. Or you can use the same as in PNG, lossless compression. The format is best suited to store texture atlases in mobile games. A good win for a mobile game.