Are you serious? Images were originally banned by an emperor, with the consent of a sham council. The 2nd council of Nicea was only possible because imperial policy changed to favor restoration. So it was the emperor behind the banning, and an emperor's regent behind that restoration.
Responding to the original question, councils are regarded as official when accepted by the whole church in the East and the Pope (theoretically representing the Church as a whole) in the West. It was accepted by the Pope, and there was reasonable acceptance in the East. Use of images was a widespread part of popular piety throughout the Church by this time, so I don't have any doubt that it meets Orthodox criteria for validity. Protestants, of course, don't necessarily use the same criteria.