This volume presents the contributions of a conference organized by the Morphomata International Center for Advanced Studies together with the Ecole Pratique des Hautes Etudes in Paris. Formats of images result from the context in which they are placed, because the place where they have to fit in determines their size. If life size was the usual scale for the antique three-dimensional portrait, deviations from it had to appear all the more striking. While an enlargement increased the effect of the portraits, a reduction of the format in many cases made it possible to change locations and circulation, for example by using the coins or gems carried on the finger. The contributions examine the interaction between format and function, which was able to bring the portrait to prominence in the most diverse areas.