When I was looking for an image to mark the feast of the Coronation of the Virgin last week I realised that the way this scene is depicted has changed significantly over the centuries. I am sure art historians have written about this as well as theologians, but it occurred to me to briefly put my thoughts together for others to read and think about.
There are many depictions of Our Lady being crowned from the high middle ages onwards. The theme was clearly very popular with patrons, and gave artists considerable scope to diplay their virtuosity.
In medieval representations the most usual image is of Christ the King crowning His Mother, usually as they sit side by side. By the later fifteenth century the image was sometimes Trinitarian, but there are also exceptional versions such as that by Enguerrand Quarton of 1454 showing two identical figures for the Father and the Son - theologically correct, but artistically rare.
Following the Council of Trent the image become smuch more consistently Trinitarian, and moves from the courtly world of the later middle ages to the billowing clouds and draperies of Mannerism and the Baroque.
Expandable illustrations of all these forms can be found at the conclusion of the Wikipedia site about the doctine of the Coronation of the Virgin, which can be accessed here.