I'm not sure how to send a 200x200 image or larger, but I've played MU Online and there you can create your own custom guild logo, that is 9x9 pixels I believe or something like that. If that would suit me, I would create a large grid where one square represents one pixel and then let the user create his logo pixel by pixel and send that information to the server and then draw the pixels on the skin of a ship, human etc. But if you need large bitmaps, this option would not be very useful.