Colour Perception

Question 1

Subtractive Colour Mixing

Answer 1

• Mixing of paints, dyes, etc
  
  • When coloured pigments selectively absorb some wavelengths and reflect others
    Cyan, magenta, and yellow

Question 2

Additive Colour Mixing

Answer 2

• When coloured lights add their dominant colour to the mixture
  
  • Red, green, blue
  • Whenever you mix primary with complementary colours you get a greyish white
  • Grey light = sum of complementary colours
    Human colour perception is based on this

Question 3

Trichromatic Theory

Answer 3

proposes that retina contains 3 different kinds of cones

Question 4

Issues with Trichromatic Theory

Answer 4

• Yellow seems to be a primary colour
  
  • Certain pairs of wavelengths produce white
• Complementarity of afterimages

Question 5

Opponent-Process Theory

Answer 5

• Each colour receptor is made up of a pair of opponent colour processes
  Blue-yellow, red-green, light-dark

Question 6

Retinal Cones

Answer 6

contain the three different types of cones, red green and blue

Question 7

Ganglion Cells

Answer 7

contain opponent pairs, respond to colour in center-surround fashion

Question 8

Afterimages

Answer 8

when a colour receptor is excited for a prolonged period of time you get a rebound effect when you stare at a neutral colour like white, so the colour receptor will go to opposite state causing complementary colour to be perceived

Question 9

High Resolution Channels

Answer 9

one cone transmit info to one ganglion cell, small receptive field

Question 10

Lower Resolution

Answer 10

• Multiple cones transmit info to a single ganglion cell

Large receptive field

Question 11

Magnocellular Layer

Answer 11

2 layers that process info about movement and depth

Question 12

Parvocellular Layer

Answer 12

4 layers, info about red/green and green/red ganglion cells, form, and fine detail

Question 13

Kaniocellular Layer

Answer 13

important for transmitting info from blue/yellow or yellow/blue ganglion cells to primary visual cortex

Question 14

Cytochrome Oxidase Blobs

Answer 14

• Regions of cytochrome oxidase containing neurons that are distributed at roughly equal intervals over PVC
  
  • Respond exclusively to colour information
    Show little to no response to shape, orientation, or movement

Question 15

Extrastriate Cortex

Answer 15

where colour is integrated with shape, orientation and movement

Question 16

Protanopia

Answer 16

red/green colour blind, red cones filled with photo pigments for green

Question 17

Deuteranopia

Answer 17

red/green colour blind, green cones filled with photo pigments for red

Question 18

Tritanopia

Answer 18

blue cones are defective, sees red, greens and greys

Question 19

Achromotopsia

Answer 19

two cone deficiency

Question 20

Tetrachromat

Answer 20

four different active cone receptors