What do the colors of the roman helmet crest mean?

There was no particular meaning to the Roman helmet crests except that if they were worn at all, each unit would have to have the same color. The ordinary soldier had a feather used on his helmet for dress parades. A centurion wore his crest in order to distinguish himself in the battle line so his men could follow him. (In battle, the Roman centurions led by example) There is no consensuses on the colors used. Sources that mention helmet feathers are divided between the colors red and yellow.