Musical iconography is concerned with the depiction of music in the visual arts. It is a discipline in its own right, covering the illustration of musicians, instruments, music-making, and the use of musical imagery.
See for example
Tilman Seebass. "Iconography." Grove Music Online. Oxford Music Online. Oxford University Press.
A major online resource for musical iconography. It is a database with links to examples of musical iconography. Fully searchable across key fields: titles, artists, people as subjects, subject keywords, instruments, schools, and locations.
The University of Melbourne Library Catalogue uses the following subject headings:
Note some titles are located in the Baillieu Library, eg Picturing performance : the iconography of the performing arts in concept and practice.