Maxon Cinema 4D is a 3D cinematic compositing tool used to mesh CGI with digital video. You're able to export high-res renders to TIFF or PNG files to make abstract fractals. I'm sure there are some tutorials around here that can educate you on how to do so. Note: my signature is an example.
All these GIMP sig tuts say open C4D and set to screen. All it seems to do is opacitate the 'c4d', and make the black background an alpha
When sig tutorials refer to C4D, they're usually talking about "effect renders" which are basically abstract renders with black backgrounds created in the program Cinema 4D. Just do a search for effect renders and you should find some good ones.
