Before Constantine
In the canonical Gospels, there is no descriptive image or wording about Jesus, just that he wears tzitzit. It is said that he came as a “light from heaven,” in the Acts of the Apostles. However, throughout history with the changing and implementing of many rules regarding art, this may be the reason there was no accurate image. The Roman Empire persecuted Christians which led to hostility against art forms and idols in particular. Jesus was represented using pictogram symbols such as a fish, peacock as well as an anchor.
After Constantine
Christianity became legal in 313 and from the middle of the 4th century new images arose. The images used the same costume that was drawn before but more of an iconography style in posing. As time passed Jesus was shown as older and in the 5th century the image of Jesus with a beard, long hair and a halo took over. This image became the standard and somewhat commercial imagery of him.