Or both?
It is a
good question. I believe that the word used is "imagos" or "imagines" and that the definition is not clear. I think that the general scholarly view is that it could refer to a variety of things - a full in-the-round
bust, relief
work, painting, etc. For example I think that the word is also used for flag-like things like the
labarum.
Roman paintings are a fascinating subject. While frescos - paintings on plaster - have survived no paintings on cloth or canvas-like materials survive. Yet we know they existed as they are referred to in
Roman literature - in houses, mounted in wagons during parades and triumphs, on the sides of buildings for special occasions. Because they no longer exist the subject is often neglected.
It would certainly seem to be easier and much much quicker to make paintings or drawings and send them in a state courier's pouch than to carve busts out of marble and ship them to different mints.
SC