将文件传递给函数的最佳方法

I'm working on a VB.NET DLL right now, and one of the functions I'm writing is supposed to take a file, and clip out an array of bytes (the method I've got works, and can be abstracted away here). What's the best way to pass a file to this function? Would passing a filename to it be best, or what would be the best way to accomplish this?I'm working on a VB.NET DLL right now, and one