User blog:Granpa/Primary colors

The primary colors that the brain (not the retina) perceives are

yellow

red

blue

combining these gives the secondary colors

orange

purple

green

One can see that these secondary colors are intermediate between the primary colors

One would assume then that combining a primary color and a secondary color would result in a color intermediate between the primary and the secondary. And indeed most do. Except for cyan. Cyan is not intermediate between blue and green.

Cyan is clearly a combination of blue and something. But what that something is is just not clear.

green	yellow- green	yellow	orange- yellow	orange	red-orange	red	magenta	purple	violet	blue	cyan
0F0	8F0	FF0	FC0	F80	F40	F00	F08	F0F	80F	00F	0FF
0F00		000F				F000				00F0	0FF0

Retina

I suggest that there were originally four primary colors and that cyan was, and still is, between blue and the fourth primary color which no longer exists (except as a component of cyan).

The original four color receptors in the retina were

green

yellow

red

blue

Originally we didnt perceive the output of the green receptor as the color green. We perceived it as a fourth primary color that no longer exists (except as a component of cyan).

For some unknown reason we eventually started perceiving the output of the green receptor as we do today as green (between yellow and blue). Therefore we no longer needed all four light receptors in the retina. So we dropped one. But instead of dropping the green receptor we dropped the yellow receptor.

Origin of the colors

Yellow, red, and blue are colorized, beautified versions of white, grey, and black. It isnt clear what the fourth primary color corresponded to.

white	yellow
grey	red
black	blue

See also

• Cyanobacteria