You can either use .tga, .jpg or .png with RBDOOM. Those textures are compressed automatically to .bimage resources if they are newer than the .bimage files.
The .bimage format is similar to .dds so you don't need .dds and the engine decides wether it is compressed to YCoCg-DXT5 or another format.
It depends on the usage in the material files. Other textures like the _currentRender are internal textures that are copied from the RGBA framebuffer.
They usually remain uncompressed for performance reasons. You can see all texture formats that are used by the console command "listImages".
The .bimage format is similar to .dds so you don't need .dds and the engine decides wether it is compressed to YCoCg-DXT5 or another format.
It depends on the usage in the material files. Other textures like the _currentRender are internal textures that are copied from the RGBA framebuffer.
They usually remain uncompressed for performance reasons. You can see all texture formats that are used by the console command "listImages".