As I understand it we see in colour because we have red and blue cones in our eyes, so what about yellow?

Question

How do you we see yellow, why not a yellow cone or have I got it wrong.

Answer 1

We have rods and cones in our eyes, three types of cones which each detect different wavelengths of light. There are red, green and blue cones, they detect wavelengths of light which are similar to the colour in their name.

Cones don't work in the dark very well, so we mostly see in black and white with usually only a small amount of colour - because rods are more sensitive therefore can detect some light in the dark, however the resolution of the image is much lower so its a less sharp image and as said above black and white.  

Answer 2

We have three types of cones, optimized to red green and blue (which is why computer generated image are often expressed in RGB).  Yellow is picked up as a weak mix of red and green.

Answer 3

Humans normally have three kinds of cones. The first responds most to light of long wavelengths, peaking in the yellow region; this type is designated L for long. The second type responds most to light of medium-wavelength, peaking at green, and is abbreviated M for medium. The third type responds most to short-wavelength light, of a violet color, and is designated S for short. The three types have peak wavelengths near 564–580 nm, 534–545 nm, and 420–440 nm, respectively. The difference in the signals received from the three cone types allows the brain to perceive all possible colors, through the opponent process of color vision.

The color yellow, for example, is perceived when the L cones are stimulated slightly more than the M cones, and the color red is perceived when the L cones are stimulated significantly more than the M cones. Similarly, blue and violet hues are perceived when the S receptor is stimulated more than the other two.

Answer 4

the cones done just see red and blue, they 'see' a range of reddish colours, and a range of blue. You see yellow when both cones send signals to your brain.