It could be done but you could encounter problems making the thumbnails.
1 - You could use the GD library to do it with 2 caveats.. firstly it's thumbnails look like crap and secondly gif support has been removed (though you can still find it or use an older version). Using the GD library really isn't an answer if you want everything to work and look great.
2 - You can use a external source to creade the thumbnails such as imagemajick or
NetPBM. You have to go out, get these packages and install them on your system first though.