Output image string in other language

Hi everybody,
I got problem with the image's string output function (imagestring()) when I try to display other language like Chinese (in Big5). It appeared to me that it couldn't decode the chinese characters to their display text. I also include some special character like "n" (new line) at the string parameter, and it didn't seem to be recognized neither.
Am I using the right function, if I wanna display other language in the php image file? If not, any alternative? Appreciated if you can help me out!
Cheer
Max