Write Binary to a FileObject

I've been searching for quite a while now, and even had a shot at it myself but I cant seem to figure out how to do it. What I want to be able to do is copy a png file from one directory in my game folder, to another area within the folder. I've looked at various resources such as the FTP one, and the TCPObject Binary Transfer which has helped me understand buffers a bit, but I still don't know how to use a FileObject to copy a png to another location.

Im assuming the thing I need to change is inside the actual writing to the file, and not the reading - so my question is, what is it that makes the fileobject write in ASCII instead of Binary. Thanks.