Module 1 - Vision, Colour, Design Guide Flashcards

0
Q

What is light?

A

Visually perceived radiant energy.

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1
Q

What are two theories about how light works?

A

Particle Theory

Wave Theory

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2
Q

What is visible light?

A

Small portion of electromagnetic spectrum from 380nm to 780nm.

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3
Q

What is a wavelength?

A

The size of periodically occurring wave, measured as the distance between any two corresponding points on successive waves.

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4
Q

What is frequency?

A

How often one part of a light wave occurs per second.

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5
Q

What is luminous flux?

A

The total amount (quantity) of light produced by a light source.

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6
Q

What is Φ the symbol for?

A

Luminous flux.

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7
Q

What is the unit of measure for luminous flux?

A

Lumen.

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8
Q

What is luminous intensity?

A

The strength of light in a specific direction.

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9
Q

What is the unit of measurement for luminous intensity?

A

Candela (cd)

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10
Q

What is the traditional term for the candela?

A

Candlepower (cp)

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11
Q

What is Illuminance?

A

The amount of light striking a surface.

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12
Q

What is the unit of measurement for Illuminance?

A

Lux or Footcandle

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13
Q

What is reflectance?

A

A measure of the ability of a surface to reflect light that arrives upon that surface.

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14
Q

What is luminous exitance?

A

Non-directional light reflected from or transmitted through a surface.

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15
Q

What is luminance?

A

Light directionally reflected from or transmitted through a surface.

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16
Q

What units are luminance expressed in?

A

Candela/sq. ft.

Candela/sq. meter

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17
Q

What are the four components of vision?

A

Source
Modifier
Eye
Brain

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18
Q

What are the optical components of the eye?

A
Cornea
Aqueous humor
Lens
Iris
Vitreous humor
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19
Q

What is the cornea?

A

A transparent membrane, the most forward surface of the eye.

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20
Q

What is the aqueous humor of the eye?

A

A clear, water-like substance that lies between the cornea and the lens.

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21
Q

What is the iris? (eye)

A

A coloured ring that that surrounds the pupil. It contains the muscles that cause the pupil to dilate and constrict to increase or decrease the amount of light entering the eye.

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22
Q

What does the lens of the eye do?

A

Changes shape to adjust the amount of optical power needed. Allows us to focus objects that lie at different distances in space onto the retina at the back of the eye.

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23
Q

What is the vitreous humor of the eye?

A

A jelly-like substance. Helps the eye to keep its shape.

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24
Q

What is the retina and what does it do?

A

The innermost layer of the eye that contains receptor cells, nerve cells, and blood vessels. The cells of the retina convert electromagnetic energy to chemical signals and, finally, to electrical impulses that nerve cells in the retina begin to process and deliver to the brain.

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25
Q

What are the two classes of visual receptor cells in the retina?

A

Rods and Cones

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26
Q

Cones are responsible for what type of vision?

A

High-level daytime photopic vision. Active in high light levels. Responsible for colour vision.

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27
Q

How many types of cones are there?

A

3

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28
Q

What light levels do rods operate under?

A

Low light levels.

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29
Q

What type of vision are rods responsible for?

A

Scotopic vision.

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30
Q

What is scotopic vision?

A

Low-level nighttime vision.

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31
Q

What type of information do rods provide?

A

The amount of light leaving a surface?

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32
Q

What is mesopic vision?

A

Neither photopic nor scotopic. How we see under many typical nighttime conditions.

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33
Q

What type of vision or cones responsible for?

A

Photopic vision/daytime vision.

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34
Q

What are cones color sensitivity?

A

Full color vision.

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35
Q

Do cones have excellent, poor, or diminished visual acuity?

A

Excellent visual acuity.

36
Q

Cones have an operating range of…?

A

Approximately 1 to 2 lx.

Under nearly all interior lighting conditions.

37
Q

Where are clones located on the retina?

A

Maximum concentration is in the fovea.

38
Q

What type of vision are rods responsible for?

A

Scotopic vision / Night vision

39
Q

What is the color sensitivity of rods?

A

Black and white vision.

40
Q

Is the visual acuity of rods excellent, very poor, or diminished?

A

Very poor visual acuity.

41
Q

What is the operating range of rods?

A

Approximately 0.2 lx. Lighting conditions of a dark night sky.

42
Q

Where are rods located on the retina?

A

Maximum concentration at the edge of the macula, with a slight reduction further out into the periphery. No rods are located in the fovea.

43
Q

What type of visions are cones and rods together responsible for?

A

Mesopic vision. Dim light vision.

44
Q

When cones and rods are working together in dimly lit conditions, what are their color sensitivity?

A

Some color vision.

45
Q

When cones and rods are working together under dimly lit conditions, what is their visual acuity?

A

Diminished visual acuity.

46
Q

What is the operating range of cones and rods when they are working together under dimly lit conditions?

A

Approximately 0.2 to 1 or 2 lx. Under bright moonlight.

47
Q

What is light adaptation?

A

Photochemical adaptation.

48
Q

What is dark adaptation?

A

Adaptation of the rods very low light levels, recurring slowly when we move from very bright environment into a very dark one.

49
Q

How long can dark adaptation take?

A

As long as 20 minutes.

50
Q

What types of environments require lighting practitioners to take into account dark adaptation?

A

Restaurants, theaters, corridors, stairs, and tunnels.

51
Q

What is the brain’s primary function in relation to vision?

A

To interpret the many signals it receives from the eye.

52
Q

What is visual acuity?

A

A measure of a person’s ability to distinguish fine details.

53
Q

What is visibility?

A

A person’s ability to distinguish critical details of an object against a background with both speed and accuracy.

54
Q

What are six primary factors that affect a persons ability to see an object or detail?

A
Size
Luminance
Contrast
Viewing time
Color
Age
55
Q

Size, when speaking of vision, refers to what?

A

The visual angle that an object makes at a particular viewing distance.

56
Q

What is luminance?

A

The amount of light leaving a surface in a particular direction, which are visual system perceives as surface brightness.

57
Q

What is a contrast?

A

The magnitude of the luminance difference between an object and its background, divided by the background luminance.

58
Q

What is positive contrast?

A

The task is brighter than the background.

59
Q

What is negative contrast?

A

The task is darker than the background.

60
Q

Older people’s vision is affected in what ways?

A

Loss of near focus.
Yellowing of the lens causing difficulty distinguishing blues and greens.
Reduced night vision.
Difficultly seeing under low light conditions.
Difficulty adapting to low light conditions.

61
Q

What age group is more susceptible to both discomfort glare and disability glare?

A

Older adults.

62
Q

What causes discomfort glare and what does discomfort glare cause?

A

Caused by bright light in the field of view.

Causes pain or visual discomfort.

63
Q

What causes disability glare and what does it do?

A

Scattered light rays the cast a veil of luminance over the retina’s field of view, reducing contrast and visibility.

64
Q

What are the luminance ratios suggested by the IES?

A

Nowhere in the visual field, were critical work is performed, should the luminance ratio between the visual task (target) and the surrounding visual field exceed 5 to 1 (target brighter than the surround) or 1/5 to 1 (target darker than the surround).

65
Q

What is the recommended maximum ratio, suggested by the IES, for situations such as office lighting and important industrial applications?

A

3 to 1 and 1/3 to 1

66
Q

What are veiling reflections?

A

Specular reflection’s that occur from polished or shiny surface.

67
Q

When specular tasks are present, the lighting system should be designed to avoid…?

A

Veiling reflections.

68
Q

What is glare?

A

Any excessively bright source of light the causes annoyance, discomfort and/or a loss of visibility.

69
Q

What is direct glare?

A

Glared due to any excessively bright source of light, coming directly to the eyes, causing discomfort and/or a loss in visibility.

70
Q

Shorter wavelengths near the 400nm end of the range will produce what colour sensation?

A

A blue sensation.

71
Q

Medium wavelengths, in the 500 to 600 nm portion of the spectrum, will produce what color sensation?

A

A green or yellow color sensation.

72
Q

Long wavelengths, between 600 and 700nm, will produce what color sensation?

A

A reddish, warm color sensation.

73
Q

What is spectral power distribution graph?

A

The composition of light from lamps and from daylight broken down into individual wavelength components and plotted on a graph.

74
Q

What does a spectral power distribution graph show?

A

The relative amount of power at each wavelength.

75
Q

What type of light does a spectral reflectance distribution graph show?

A

Reflected light.

76
Q

What type of light does a spectral power distribution graph show?

A

Generated light.

77
Q

What are the two types of color mixing?

A

Additive color mixing and subtractive color mixing.

78
Q

Is color an intrinsic property of light or is it a perceptual phenomena?

A

A perceptual phenomenon.

79
Q

What is chromaticity?

A

An objective specification of the quality of a color or a light source regardless of the luminance.

80
Q

What are two characteristics of chromaticity.

A

Hue and saturation.

81
Q

What is color temperature used to describe?

A

The overall color tone of emitted light, including the appearance of the lamp when viewed directly.

82
Q

What is color rendering index used to describe?

A

How objects will look when lighted by a lamp.

83
Q

What is the “color temperature” of a light source?

A

A numerical measurement of its color appearance.

84
Q

If an iron horse shoe is heated how will the color change as the temperature rises?

A

Red to orange to yellow to blue.

85
Q

How is color temperature expressed?

A

Degrees kelvin. (K)

86
Q

What is CRI used to quantify?

A

A light sources ability to produce color in objects.

87
Q

How is CRI expressed?

A

On a scale of 0 to 100 calculated as an average.