PSY280 Unit 2

color is a ____ property

psychophysical

3 steps to color perception

detection, discrimination, appearance

3 types of cones

S, M, L

scotopic lighting conditions

dim light levels

rods are sensitive to ____ light levels

scotopic

all rods have _____ to wavelength, making it impossible to discriminate light

same sensitivity

rods contain the ____ photopigment molecule

rhodopsin

photopic lighting conditions

bright enough light to stimulate cones

s cone wavelength and colour

420 nm, blue

m cones wavelength and colour

535 nm, green

l cones wavelength and colour

565 nm, red

univariance

different wavelength-intensity combinations can elicit exactly the same response from a single type of photoreceptor

trichromacy/Young-Helmholtz theory

theory that colour of any light is defined by the outputs of 3 receptor types (3 cones)

Maxwell’s color matching experiments

3 colours mixed together to match a single colour

additive color mixing

mixture of light, where effects of lights add together

metamers

different mixtures of wavelengths that look identical

subtractive color mixture

mixture of pigments

pigment

substances that absorb light at some wavelengths and reflect light at others

reflectance curve

proportion of light at different wavelengths that is reflected from a pigment

additive color mixing with pigments uses which colors? do the colours overlap?

yellow and blue, no

dithering uses what kind of color mixing

additive

dithering results in a

reduction of number of colors needed

mixing of pigments is what kind of colour mixing

subtractive

color space

3 dimensional space established because color perception is based on output of 3 cone types

lms color space

defined by responses of the 3 types of cones

dkl color space

computes contrast in the lms color space

isoluminant plane is formed of

L-M contrast and S-(L+M) contrast

isoluminant plane means all colours appear to have the same

brightness

luminance axis is made up of

(L+M)

CIELAB color space based on these 3 color opponencies

lightness of colour, position between green and magenta, position between blue and yellow

the CIELAB color space is ___ scaled

non-linearly

RGB color space

defined by outputs of long, medium, and short wavelength lights for additive color mixing

the RGB color space looks like a

cube with white and black as diagonally opposite corners

HSB color spaces

defined by hue, saturation, and brightness

HSB color spaces are used in

graphic design

HSB color spaces are shaped like

2 cones

CMYK color space

made up of cyan, magenta, yellow, and black

CMYK color spaces are designed for what kind of color mixing

subtractive

Y’UV color space

analog color space invented to transmit TV signal color on top of existing black and white signal

YCbCr color space

digital color space for digital photography

cone-opponent cell

neuron whose output is based on a difference between sets of cones

opponent color theory

theory that perception of color is based on the output of red-green, blue-yellow, and black-white opponency

afterimage

visual image seen after stimulus is removed

negative afterimage

afterimage whose polarity is the opposite of the original stimulus

there is no way of explaining afterimages through ____ alone

trichromacy

color contrast

color of one region induces the opponent color in a neighboring region

color assimilation

2 colors bleed into each other, each taking on some of the chromatic quality of the other

illuminant

light that illuminates a surface

color constancy

tendency of a surface to appear the same color under a wide range of illuminants

photoreceptor density is highest in the

fovea

in general, does everyone see colors the same way?

yes

how much of the male population has a color vision anomaly

8%

how much of the female population has a color vision anomaly

0.5%

deuteranope is due to the absence of what type of cone

M

protanope is due to the absence of what type of cone

L

tritanope is due to the absence of what type of cone

S

color-anomalous color blindness is when 

someone has 2 types of cones that are so similar that they can’t discriminate between them

cone monochromat is when someone

only has 1 cone type

cone monochromats see the world in

black and white

rod monochromats do not have any

cones

rod monochromats are usually visually impaired in

bright light

colorblindness conditions are ____, and are passed on the ___ chromosome

hereditary, X

achromatopsia is the inability to perceive colors due to

damage to the central nervous system

naming of colors can impact the ____ of colors

perception

images that are projected onto the retina are ____

non-Euclidian

monocular depth cue

depth cue that is available when using 1 eye

binocular depth cue

depth cue relying on info from both eyes

monocular depth cues include

nonmetrical, relative, and absolute metrical depth cues

nonmetrical depth cues give info about

relative depth order but not magnitude of depth

relative metrical depth cue gives

quantitative info about relative depth

absolute metrical depth cue gives

quantitative info about absolute distance

occlusion

cue to relative depth order when an object obstructs view of part of another object

nonmetrical depth cues include

occlusion, aerial perspective, and texture gradients

aerial perspective is the depth cue based on

scattering of light by the atmosphere

texture gradient is a depth cue based on

geometric fact that items of same size form smaller images when further away

relative metrical depth cues include

relative size, relative height, motion parallax

relative size is a ____ of size between items without

comparison, knowing absolute size of either item

relative height says more distant objects are ___ in the visual field

higher

absolute metrical depth cues include

familiar size

familiar size is a depth cue based on

knowledge of the typical size of objects

is motion parallax monocular or binocular

monocular

motion parallax is a depth cue based on ___ where closer objects appear to ____

motion, move faster

pictorial depth cue is used by

artists

linear perspective is a depth cue based on the fact that

parallel lines in the 3d world seem to converge in 2d images

vanishing point

point where parallel lines seem to converge

anamorphosis

use of linear perspective to create 2d image that only looks correct from a certain angle

2 ways we combine information from our 2 eyes

binocular summation and binocular disparity

binocular summation

information from both eyes is considered equally and summed up

binocular disparity

comparing different information between 2 eyes

binocular summation is useful for ____

prey

binocular disparity requires

a lot of overlap between 2 eyes

binocular disparity is useful for ___

predators

binocular disparity is the basis of ___

stereopsis

stereopsis

perception of 3 dimensions

2 stages of stereopsis

selection of a depth surface (horopter), computation of binocular disparity providing depth info relative to horopter

horopter

surface of 0 disparity, a particular surface in 3d space

accommodation

lens changing focus and size

convergence

ability of 2 eyes to turn inward to reduce disparity

divergence

ability of 2 eyes to turn outward to reduce disparity