That is an odd question, you can display an image however you like. Keep in mind that this is working with in the Linux distribution and not anything specific to the Arduino compatibility layer. So anything running on Linux can use it. You could use one of the common Linux media players or picture viewers. I know for sure that GIMP works but that is more heavyweight than you need. If you want to write your own, either Qt or Gtk+ are good choices for a UI. I have run applications using both toolkits on the Galileo without any problems.
Keep in mind the refresh rate is slow due to being over SPI and the Galileo has high latency on SPI calls. Still photos are fine but I wouldn't recommend video. You might even have performance problems on the Quark trying to decode the video.