STRPTR name = GetImageFormat(APTR handle);
HWEXT_IMAGE_FORMATextension bit has been set. See Extension plugins for details. If that is the case, this function must return a null-terminated string containing the name of the format of the image file handle passed in
handle. The string returned by this function can be retrieved from Hollywood scripts by querying the
#ATTRFORMATattribute on image-based objects like
#BGPIC. The string you return must be valid until FreeImage() is called on the image handle passed to this function.