Color Theory

Trichromatic Theory (Young-Helmholtz theory)

n Across fiber patterning

n 3 Types of cones

q Short (blue) – 420-450 nm

q Medium (green) – 525-535 nm

q Long (red) – 555-565 nm

n Brain can differentiate between wavelengths by pattern of firing from 3 cones

Opponent Process Theory

n Color Blindness – dichromat - missing 1 cone (red/green or blue/yellow)

n Afterimage

n Ganglion cells – fire to one color, inhibitory to other color

Issues with Opponent Process

n Need to be able to carry info about color and brightness and shape, motion, etc.

n S cones less common than M and L cones – how perceive short wavelengths as well?

n How get from 3 cones to all colors in spectrum?