Were you aware that Maxwell gave a lecture to the Royal Society in
England on this very subject of primary colours?

This has been beaten by an Englishman, Claude Friese-Greene, in 1927
with an additive system of only two colors: red and green. Note,
there is no blue, no yellow. I will quote a fuller description below.

For those who believe their eyes and the yellow of blond hair, and the
blue of the sky check out 5 seconds into:
Helmsdale, Scotland (1926) at youtube:
http://www.youtube.com/watch?v=dVy5gMTps3Q
There are also natural skin tones and reds too.

One can consider the blue of the Thames river in
The Thames opposite the Tower of London, London (1926)
http://www.youtube.com/watch?v=7BCfx651YQY

Then there is the classic
The Open Road London (1927)
http://www.youtube.com/watch?v=TwahIQz0o-M

Taken from Claude Friese-Greene's Colour Process
By BBC History:
http://www.bbc.co.uk/history/program...ocess_03.shtml
The film he used was panchromatic and so able to record colour in tones of black and white. He also used a revolving colour filter wheel on the lens with one red filter, one orange and the other clear.

The processed film was then stained with red and green using a mechanical process on alternate frames. It was then meant to be down to the viewer to effectively do the rest - when projected at a fast enough speed, the eye plays a trick on the brain and creates the illusion of a broader colour spectrum.

So, the primary colors your eye would believe come from
red/orange/green - something more suitable to Halloween than a colour
travelogue.

The original Technicolor (1916) was similar with an identical color
process (red and green) which had two separate color frames with
overlapping projection. Needless to say, the Technicolor we are used
to abandoned the first three versions of the two color methods to give
us the three color "The Adventures of Robin Hood."

I will repeat the cogent point about colour:
the eye plays a trick on the brain and creates the illusion of a broader colour spectrum.

73's
Richard Clark, KB7QHC