A million colours; single photons; galactic realms quintillions of miles distant â€“ not bad for the blobs of jelly in our eye sockets, wired to a 1.4 kilogram sponge in our skulls.
To add a bit of context:
- Photon wavelengths: about 380 to 720 nanometers
- Colors: about 1,000,000 (100 color shades per cone x 3 cones)*
- Sensitivity: one photon
- Distance: one photon (as long as a photon reaches our retina)
- Visual Acuity: 120 pixels per degree of arc (fingernail at arm’s length with 60 horizontal and 60 vertical lines)
Our visual system is quite a remarkable design.
* Tetrachromats are people who have an extra fourth cone cell allowing them to perceive 100 million colors.