Combine red and violet diodes

[FireMyLaser]

Minimum 2 wavelengths is for a specific colour. Look on the diagram posted earlier. The colours right on the 488-660 line show what colours those 2 wavelengths can make by varing the ratio between them. To make literally every colour you need all visible wavelengths and total control of them. That is not practical, but can be simplified to using just 3 RGB wavelengths. You just lose the colours outside the triangle.

 

[Alaskan]

I find this a interesting topic, hoping it branches into how our eyes work with our brains to perceive colors this way.

 

[paul1598419]

That is not a big secret. It has to do with cones versus rods in your central vision. The cones see colors. The rods are primarily monochromatic and are more densely populated in the peripheral vision.

 

[Alaskan]

I find the non-secrets of this subject interesting. There is a lot more to this than those aspects alone:

There is a lot more to color perception than the eye too, see this: