A "proper icon" is an image that is in conformity with the 7th Ecumenical Council, not necessarily with the more crystallized tradition of the Christian East, with its own "canons" and such. The council was not the affirmation of the Byzantine-style of Christian art, but was an extension of the doctrine of the Incarnation and our beliefs about matter and veneration of the saints.
Their conclusion: "As the sacred and life-giving cross is everywhere set up as a symbol, so also should the images of Jesus Christ, the Virgin Mary, the holy angels, as well as those of the saints and other pious and holy men be embodied in the manufacture of sacred vessels, tapestries, vestments, etc., and exhibited on the walls of churches, in the homes, and in all conspicuous places, by the roadside and everywhere, to be revered by all who might see them. For the more they are contemplated, the more they move to fervent memory of their prototypes. Therefore, it is proper to accord to them a fervent and reverent adoration, not, however, the veritable worship which, according to our faith, belongs to the Divine Being alone — for the honor accorded to the image passes over to its prototype, and whoever adores the image adores in it the reality of what is there represented."
This included carvings, statues, etchings, etc., anything the depicted the saints and events of sacred history. It is not the more pronounced style and tradition of the East that is binding upon the Church. Any "holy image" is what's acceptable to Orthodox Catholics, no matter what form it takes.