The page links to a New York Times article which states the following;
"Pigment tests and scientific analyses of the illustrated manuscript have revealed that the illustrations of A.D. 586 were repainted after it entered the Medicis' Laurentian Library in the 16th century, where it remains today. The oversized book, originally produced in a Syrian monastery, includes the first dated pictorial representation of the Crucifixion. Tests revealed, among other things, that in the repainting, Jesus's curly red hair was restyled as black and straight."This is fascinating as it would suggest that the earliest dated depiction of Jesus actually showed him with red hair.
It makes a refreshing change from Judas being depicted as a redhead xD