tweed 5 colour vision

visible light

400 nm (violet) to 700 nm (red)

why did evolution give us this range

sunlighhts power peaks there, also sea water is mosty transparent <500 nm

3 cones

red (63%), green (31%) and blue (6%), were called trichromats

rhodopsin

prefers blue-green wavelenghts

melanopsin

prefers blue

spectral colours

the colors that can be produced by a single wavelength of light, typically represented in the visible spectrum.

extraspectral colours

colors that cannot be produced by a single wavelength,needs a mix, such as purple and brown.

excited by red and green light

R + G cells, or yellow channel

excited by red, inhibited by green

R - G, or red-green opponent channel

excited by blue, inhibited by red and gree

B - R - G, B - (R + G), or blue-yellow opponent channel.

daltonism

red-green colour blindness

reflectance

tendency to reflect certain wavelenghts of light and absorb others, influencing perceived color.

colour constancy

The ability of the visual system to perceive colors of objects as relatively constant under varying illumination conditions.