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

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

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

Retina

The original four color receptors were

yellow

green

red

blue

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

Eventually we started perceiving the output of the green receptor as between yellow and blue (as we do today). 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