Color Vision txtbk Flashcards

1
Q

Color vision:

A

The ability to see differences between lights of different wavelengths

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2
Q

Qualities that describe how we perceive color:

A

Hue, Saturation, Brightness

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3
Q

Two physiological mechanisms that create our experience of color:

A

Trichromacy and Opponency

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4
Q

Color constancy and Light constancy

A

Our ability to see things as having the same color and lightness under different conditions

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5
Q

Color vision deficiencies/ “colour blindness”:

A

condition in which people experience partial or total loss of their ability to see color

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6
Q

What did Isaac Newton postulate?

A

Our perception of color comes from the interaction between receptors in the eyes and the wavelengths of light reflected from the surface of objects - a specific experienced color is evoked by specific wavelengths present in the light

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7
Q

The visible spectrum ranges from :

A

400 to 700 nm

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8
Q

Visible spectrum:

A

The portion of the electromagnetic spectrum in the range of about 400 to 700 nm; people with normal color vision perceive differences in wavelengths as differences in color

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9
Q

Is color in material things

A

color is NOT in light or material things: color is a perceptual experience evoked by specific wavelengths of light reaching our eyes

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10
Q

Spectral power distribution:

A

The intensity (power) of a light at each wavelength

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11
Q

heterochromatic light:

A

Light that consists of more than one wavelength

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12
Q

monochromatic light:

A

Light that consists of only one wavelength

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13
Q

The SPD of a monochromatic light:

A

Is a vertical spike

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14
Q

sunlight, incandescent bulbs and fluorescent bulbs all emit what is called :

A

White light

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15
Q

White light is heterochromatic light that:

A

(1) contains wavelengths from across the entire visible spectrum
(2) has no really dominant wavelength

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16
Q

The SPD of an idealized white light would be:

A

A horizontal line: A light in which all wavelengths across the visible spectrum have exactly equal power

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17
Q

The SPD of __ is quite close to an idealized white light

A

sunlight

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18
Q

SPD of light from incandescent bulb is

A

more intense toward the yellow and red end of the spectrum

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19
Q

SPD of light from a fluorescent bulb:

A

has spikes at the “short” and “medium” wavelengths that make fluorescent light somewhat more bluish than sunlight

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20
Q

Achromatic light is synonymous with:

A

white light

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21
Q

Achromatic light:

A

heterochromatic light containing wavelengths from across the visible spectrum, with NO really DOMINANT wavelengths: perceived as more or less colorless

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22
Q

A graph of the spectral reflectance of a surface shows:

A

The percentage of light at each wavelength that the surface reflects rather than absorbs

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23
Q

Black, gray and white paper have similarly flat reflectance curves, which means:

A

They reflect the same percentage of all wavelengths - but white paper reflects overall much more light than black paper

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24
Q

The perceived colour of things depends on:

A

(1) The SPD of the light source
(2) How things reflect light

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25
Q

The way objects reflect light depends on:

A

The molecular structure of the surface which determines its spectral reflectance, the proportion of light at each wavelength that the surface reflects rather than absorbs

26
Q

something we perceive as green reflects a __ percentage of the light in the “green” portion of the spectrum in the range of 500-550 nm, and a ___ percentage of most other wavelengths

A

Something we perceive as green reflects a GREATER percentage of light in the “green” portion of the spectrum and a LOWER percentage of most other wavelengths

27
Q

Some surfaces (white, grey, black paper) have reflectane curves that are approximately horizontal lines indicating that:

A

they reflect about the same percentage of all wavelengths: however, they DIFFER in the AMOUNT of light they reflect
ex: black paper absorbs more than 90% of the incident light and reflects less than 10% while white paper reflects 80% or more at almost all wavelengths

28
Q

What is in the meaning of the term visible spectrum?

A

The ability to see differences between lights of different wavelengths

29
Q

What is the difference between spectral power distribution and spectral reflectance?

A

SPECTRAL POWER DISTRIBUTION: The intensity (power of a light at each wavelength in the visible spectrum)
SPECTRAL REFLECTANCE: Proportion of light that a surface reflects at each wavelength

30
Q

Light is an:

A

Electromagnetic wave

31
Q

Light of different wavelengths is perceived as:

A

Different colours

32
Q

Light is usually __ not usually ___

A

Light is usually heterochromatic, not monochromatic

33
Q

Colour is a __ construct

A

colour is a PERCEPTUAL construc

34
Q

Color is NOT a ___ property

A

Color is NOT a physical property

35
Q

Our perceptual experience of colour can be represented as two dimensions/properties:

A

(1) hue
(2) saturation

36
Q

Hue is commonly referred to as :

A

colour

37
Q

Saturation:

A

The “purity” or “vividness” of the hue

38
Q

CIE colour space developped by the comission internationale de l’eclairage is a :

A

Standardized colour space where any colour can be represented by a pair (X,Y) of coordinates

39
Q

Can brightness be represented on the CIE color space?

A

if we want to represent brightness we would need a third color dimension

40
Q

The center of the CIE color space is where we see:

A

Colorless or “white” light

41
Q

At the bottom right if the CIE color space we find:

A

non spectral purples

42
Q

Non spectral purples hues that:

A

can NOT be evoked by a single wavelength light (monochromatic light)

43
Q

We can perceive nonspectral purples if we see :

A

light of different wavelengths mixed together

44
Q

We perceive heterochromatic light to have the color corresponding to:

A

its dominant wavelength

45
Q

Perceptual experience of light is extremely

A

subjective

46
Q

The primary colors are:

A

red, green and blue

47
Q

Additive color:

A

We can create the perception of different colours by mixing the “primary” additive colors

48
Q

additive color works best with:

A

“pure” monochromatic light

49
Q

One of the most common applications of additive color is:

A

digital displays

50
Q

Subtractive color relies on:

A

the light being absorbed rather than light being produced/transmitted

51
Q

In additive color mixture, we want:

A

highly monochromatic and highly saturated pimary color (we want opposite for substractive color)

52
Q

In subtractive color mixture we want:

A

heterochromatic light, not saturated

53
Q

subtractive color will absorb:

A

most of the spectrum and allow particular band to pass through
ex: blue paint absorbs longer wavelengths and reflects the short

54
Q

nonspectral purples are colors that:

A

cannot be evoked by monochromatic light

55
Q

Two objects of the same hue but different saturation would be perceived as :

A

more or less vivid but the same “colour”

56
Q

computer screens are an application of:

A

additive color

57
Q

metamers:

A

two stimuli that are physically different but perceived to be the same

58
Q

we need at least __ colors mixed together in order to recreate the full spectrum of visible light

A

three colors mixed

59
Q

Evidence that we need three primary colors to match the wavelengths from across the spectrum of visible light comes from:

A

metameric color-matching experiments

60
Q

Metameric color-matching experiments:

A

people were trying to match a single monochromatic light source with a mixture of other light sources