Lecture 19 - Lecture 21: Vision Flashcards Preview

Uncategorized > Lecture 19 - Lecture 21: Vision > Flashcards

Flashcards in Lecture 19 - Lecture 21: Vision Deck (79):
1

Light is a form of electromagnetic radiation generated by the oscillation of electrically charged particles called __________?

Photons

2

What are the two most important qualities we perceive from light?

Color and brightness

3

The length of the light's wavelength produces

Color

4

As the length of the light wave increases, ___________________________

The sensation of the color changes

5

The brightness of a couloir is related to it's ____________, which is directly proportional to the density of photons in the wave.

Amplitude

6

The more photons in the wave, (brighter/lighter) the light or color will appear to be.

Brighter

7

Light is a pattern of _________________ and _______________, along the many wavelength they create, that allow us to see the shapes and surfaces of objects.

Reflection and absorption

8

What is used to measure light?

Nanometer

9

Tendency for colors to remain fix despite changes in illumination In which they are embedded

Color constancy

10

Two types of reflection

1. Speculation reflection
2. Diffuse reflection

11

What is specular reflection

Mirror like reflection

12

What is diffuse reflection

Reflection of the rough

13

The first step in color perception begins with the _________ in the retina

Cones

14

What are the 3 different types of cones?

1. Absorbs light in short wavelengths (445 nm-blue)
2. Absorbs light at medium wavelengths (535nm-green)
3. Absorbs light at long wavelengths (570nm-red)


Red sensitive cones do not respond exclusively to long wavelengths of light, they just respond better - the same principle holds for the other 2 cones p. 71

15

We detect all these different wavelengths because the light energy reaching our eyes is __________ by the cones into neural impulses

Transduced

16

______________ are special molecules imbedded in their membrane consisting of opsin and retinal

Photopigments

17

What are the 3 trichromatic colors?

Red, green, and blue

18

The trichromatic theory is also known as?

Young-Helmholtz

19

What is the problem with the trichromatic theory?

It could not explain the effect of negative after-images

20

What is the most common form of color blindness

Red (protanopia) - green (dueteranopia)
followed by the rarer blue-yellow form
(no such thing as red -blue or green-yellow color blindness)

21

Who proposed the opponent theory of color vision

Weald Hering

22

Where does yellow come from?

It is made up from inputs arriving from the red and green cones

23

The perceived color of an object remains the same under very difficult lighting conditions

Color constancy

24

What colors do people who suffers are red-green color blind sees?

Blue, yellow, and grey

25

Why does red-green color blindness predominantly affect the males

Because the protan and duet an genes are located on the X-chromosomes, of which men have one and women have two. Women are rarely red-green blind because if one of their X chromosome is defective the other one can compensate for it. Daughters of men who handed down color blindness to his children will normally be unaffected

26

What type of color blindness would it be if a person lacks blue cones (unable to distinguish between blue and yellow).

Tritanopia

27

_________________ causes total color blindness

Achromatopsia

28

First region to receive input from the lateral geniculate nucleus

Visual area 1 or v1 or area17 or primary visual cortex

18 and 19 or V2 and V3 make up the visual association cortex

29

Condition where people suffer from bilateral damage to the posterior regions of the parietal lobes

Balint's syndrome

30

Difficulty in shifting one's gaze into a new stimulus. Difficulty in focusing in on a particular object. Their eyes wander around so that objects came into view for a while and are then replaced by others

Ocular apraxia

31

Inability to reach for objects under visual guidance. Result to person fumbling and misreaching for objects and being unable to point accurately to a visual stimulus although the they can see it clearly

Optic ataxia

32

A person's inability to see the totality of their visual scene. Have a very narrow visual attention field which will result in their being unable to see two objects at once. E.g. Toothbrush and pen

Simultanagnosia

33

A person being unable to recognize the faces of their family and friends

Prosopagnosia

34

The stimulus for activity ting the visual system is ________?

Light

35

What makes a colored objected appear to be that color (I.e. Blue)?

When light strikes an object, the long wavelength is reflected and the other wavelength is absorbed

36

Sensitive to light at low energy

Rods

37

What are combined pigments?

Selectively removing all the wavelengths of light

38

What are the 2 main receptor types

1. Cones
2. Rods

39

What is the difference between cones and rods

Cones - daylight; gives color
Rods - nighttime

*cones sensitivity to light is lower than the rods

40

What are the 4 receptors

1. Short wavelengths (445 nm-blue)
2.medium wavelengths (535nm-green)
3. long wavelengths (570nm-red)
4. Rods

41

What the peak of the cone tells you?

Sensitivity

42

What states that all absorbed photons generate the same response independently of wavelength

Principle of univariance

43

________________ same pattern of activation in the cone and will have the same colour experience.

- why monitors, colored TVs, cameras, etc. work

Metameters

44

_______ is all about trichromatic. Type of adaptation. Receptors become unresponsive

Color after image

45

What are the 3 opponent aces that you need? And what is the neutral color?

1. Blue-yellow
2. Red-green
3. Black-white


-Grey is neutral

46

What is color?

Capacity to experience differences between wavelengths

47

Why do you experience color?

Because you have more than 1 cone while rods look at the same visible spectrum

48

What is color vision?

Capacity to experience different wavelength of light

49

What does trichromatic count for?

Photons

50

What is a single wavelength of light

Saturation

51

Mixing colors from any points on the opposite sides of the perimeter takes you through a __________. What colour is it?

Neutral point; grey

52

What theory states that certain colors cancels each other out

Opponent process theory

53

What corresponds grossly to the height of the 3D representation?

Brightness

54

Corresponds to the radial distance from the achromatic point

Saturation

55

Equal intensity plane of colour space

Isssiluminate plane

56

What colors you get from an unusual spectrum

Spectral locus

57

The 4 colors: red, green, blue and yellow are part of the spectral locus

Unique hues

58

What do you mean by impure red?

Impure because it's a mixture of red and blue

59

A color that is evoked by a single wavelength of light in the visible spectrum

Spectral color

60

Most saturated point

Grey

61

Subtractive color can be used for?

Printing

62

What is used for printing?

CMYK

63

Used for presentations?

RGB

64

What is the principle that says that it has the same colour but the surround affects it?

Simultaneous contrast

65

How do you decompose luminance into their physical sources?

Using Shadows

66

What are shadows?

Difference on how they are illuminated

67

What are the 4 edge classification problem?

1. Reflectance (changes in surface lightness or color)
2. Shape (folds)
3. Illumination (shadows; spotlights)
4. Occlusions (which could include one or more f the above)

68

What is illiuminance

Light falling on a surface

69

What is reflectance?

Proportion or percentage of light that a surface reflects

70

What is luminance?

Total amount of light reaching the eye

71

What is the formula for luminance

Luminance = illiuminance X reflectance

72

What is important about shadows?

The edge of the shadow

73

Yellow and blue will give you what color?

Grey

74

what is a single (different) wavelength of light at a particular intensity (say 550)

photoreceptor curves

75

what do you call the total response in all lights of each individual wavelength?

weighted sum

76

what does photoreceptor curves mean?

the curve tells the weights of the wavelength

77

how many receptors do you need to tell about the wavelength composition of light?

you need the 3 receptors/cones

78

what do you experience when you excite the cones in the same way. Thi is why monitors, TV's, colour cameras film, etc worl

metamers

79

mixing colors from any points in the opposite sides of the perimeter takes you through a neutral point. what colour would this be?

grey