Ah, OK, Tiff isn't a particularly simple format but the article you point to just hard-code a given variant of this format.
Doing such low level file writing is quite hard, particularly because most image file formats compress the data, in a not so simple way. You can also use JAI (Java Advanced Imaging library) to control with precision the parameters of the generated files.
Anyway, to write binary data, you can use saveBytes() or dive into the complexities of Java I/O (creating an output stream, etc.).