Which image filetypes are supported when you pass through a byte[]?
In fact, just anything which matches image/*. See here for a list. You're only dependent on the webbrowser/client used whether it supports the image type.
By the way and to be sure: you can't let the value point to a byte[]. It must point to an URL which returns the byte[] in question. A servlet is perfectly suitable for this. Here is a basic example.