l9- colour perception

Question 1

NATURAL LIGHT + colour perception

natural light

Answer 1

• made of diff wavelengths
• monochromatic length (1 wavelength,640mm)=rare in nature
• every object reflects a mix of WLs

Question 2

NATURAL LIGHT + colour perception

colour

Answer 2

• interaction between physical properties of object n visual system

Question 3

photoreceptors in the retina

Answer 3

• 4 types: S-cones, rods, M-cones, L-cones
• WL sensitivty- each type responds to diff WL ranges

Question 4

prinicple of univariance

Answer 4

• diff WL+intensity combos can make the same response from a photoreceptor
• photoreceptor only signals how much light it absorbs, not the wl
• 1 receptor cannot produce colour alone

Question 5

trichromacy

colour vision

Answer 5

• depends on ratio of 3 cone outputs
• percieved colour depends on response of 3 cone types to object spectral reflectance
• any colour can be matched using a combo of 3 primary colours: red, green blue

Question 6

trichromacy

trichromacy theory of colour vision

Answer 6

• young-helmholtz 1800s
• based on colour matching experiments
• validated by maxwell
• white or grey=percieved when 3 cone types=stimulated equally

Question 7

trichromacy

metamers

Answer 7

• consequcne of univarence+trichromacy
• 2 or more mixs of lights look identical if they excite cones equally
• physically diff, perceptually equivalent