Origins of the \'Hollywood\' Roman salute?

[Tarbicus]

It has been suggested in the past that perhaps it was customary for a lower rank to remove his helmet as a sign of respect (I think I may have said it, but can't find it right now). One result of this is that the higher rank would stay more protected. Perhaps under arms, particularly during battle or campaign where it could be impractical and even downright dangerous, this was replaced by a gesture signifying the removal of the helmet?

A more modern equivalent can be seen in the Naval services:
[url:1hn69fd0]http://www.readyayeready.com/tradition/customs-of-the-navy/5-salutes-and-ceremonial.htm[/url]

Until about 1800 the normal type of salute was the raising of the cap, originating with the removal of the steel helmet. Merely touching the cap became a recognized alternative. Admiralty regulations of 1882 defined the salute as removing the cap, or at least touching the brim between the index finger and thumb. This is a clear indication of the origin of the naval type of salute, though other more interesting reasons have been offered. One of these is that in the year 1890 Queen Victoria, renowned for her primness and femininity, while inspecting a body of her sailors turned out in their best uniforms, was horrified at the sight of their tar-stained hands, and ordered that in future the naval salute was to be with the offending palms turned down.

I know they are centuries apart, but if a reason for red being the colour 'under arms' as suggested by many was for practical reasons then the same could apply (possibly - I emphasise) to the salute. But the removal of the hat as a mark of respect is also a Christian tradition which is full of Roman influences.