‘Black Out Software’ was made for Alexander Schubert. It allows everyone (who owns a Mac or Max/MSP) to produce a score like Alexander Schuberts ‘Black Out BRD’. A midifile which is fed into the application, is kind of reversed, so that all pitches which were present in the midifile will be left out and replaced by all other pitches, which haven’t been there before.
Give it a try 🙂