Color Perception and Applications SIGGRAPH 99 Course: Fundamental - - PDF document

color perception and applications
SMART_READER_LITE
LIVE PREVIEW

Color Perception and Applications SIGGRAPH 99 Course: Fundamental - - PDF document

Color Perception and Applications SIGGRAPH 99 Course: Fundamental Issues of Visual Perception for Effective Image Generation Penny Rheingans University of Maryland Baltimore County Overview Characteristics of Color Perception


slide-1
SLIDE 1

Color Perception and Applications

SIGGRAPH ‘99 Course: Fundamental Issues of Visual Perception for Effective Image Generation

Penny Rheingans

University of Maryland Baltimore County

Overview

  • Characteristics of Color Perception
  • Mechanisms of Color Perception
  • Color Specification
  • Using Color to Represent Information
slide-2
SLIDE 2

Characteristics of Color Perception

  • Fundamental, independent visual process

– after-images – color deficient vision

  • Relative, not absolute
  • Interactions between color and other visual

properties

Physiology: Receptors

  • Rods

– active at low light levels (scotopic vision) – only one wavelength sensitivity function

  • Cones

– active at normal light levels – three types: sensitivity functions with different peaks

slide-3
SLIDE 3

Cone Sensitivity Functions

  • Glassner ‘95, p. 16.

Physiology: Ganglia

  • Transform incoming SML into opponent color

responses

– G - R – Y - B (Y = R+G) – W (W ≅ R+G)

  • Characteristics

– concentric receptive fields – logarithmic response of receptors – adaption

Long (R) Medium (G) Short (B)

+

  • R - G

Y-B Achromatic Yellow

slide-4
SLIDE 4

Physiology: Brain

  • Lateral geniculate nuclei

– assemble data for single side of visual field – 2 monochromatic layers => magnocellular path – 4 chromatic layers => parvocellular path

  • Visual cortex

– visual area 1: blobs – visual area 2: thick stripes – visual area 4

Visual Pathway

  • Murch, ‘87.
slide-5
SLIDE 5

Parvocellular Division

  • Role in vision

– discrimination of fine detail – color

  • Characteristics

– color: sensitive to wavelength variations – acuity: small RF centers – speed: relatively slow response

Color Models

  • Device-derived

– convenient for describing display device levels – RGB, CMY

  • Intuitive

– based in familiar color description terms – HSV, HSB, HLS

  • Perceptually uniform

– device independent, perceptually uniform – CIELUV, CIELAB, Munsell

slide-6
SLIDE 6

Color Models

  • Device-derived

– convenient for describing display device levels – RGB, CMY

  • Intuitive

– based in familiar color description terms – HSV, HSB, HLS

  • Perceptually uniform

– device independent, perceptually uniform – CIELUV, CIELAB, Munsell

slide-7
SLIDE 7

Color Models

  • Device-derived

– convenient for describing display device levels – RGB, CMY

  • Intuitive

– based in familiar color description terms – HSV, HSB, HLS

  • Perceptually uniform

– device independent, perceptually uniform – CIELUV, CIELAB, Munsell

slide-8
SLIDE 8
  • Hill et al. ‘97, pg. 136

Uses of Color

  • Show classification
  • Mimic reality
  • Show value
  • Draw attention
  • Show grouping
slide-9
SLIDE 9

Uses of Color

  • Show classification
  • Mimic reality
  • Show value
  • Draw attention
  • Show grouping
slide-10
SLIDE 10

Uses of Color

  • Show classification
  • Mimic reality
  • Show value
  • Draw attention
  • Show grouping
slide-11
SLIDE 11

Uses of Color

  • Show classification
  • Mimic reality
  • Show value
  • Draw attention
  • Show grouping
slide-12
SLIDE 12

Uses of Color

  • Show classification
  • Mimic reality
  • Show value
  • Draw attention
  • Show grouping
slide-13
SLIDE 13
  • Ware and Beatty ‘85, p. 22

Perceptual Distortions

  • Color-deficiency
  • Interactions between color components

– saturation - brightness (Helmholtz-Kohlraush effect) – brightness - hue (Bezold-Brucke Phenomenon)

  • Simultaneous contrast

– brightness – hue

  • Small field achrominance
  • Effects of color on perceived size
slide-14
SLIDE 14

Bezold-Brucke Phenomenon

  • Hurvich ‘81, pg. 73.

Perceptual Distortions

  • Color-deficiency
  • Interactions between color components

– saturation - brightness (Helmholtz-Kohlraush effect) – brightness - hue (Bezold-Brucke Phenomenon)

  • Simultaneous contrast

– brightness – hue

  • Small field achrominance
  • Effects of color on perceived size
slide-15
SLIDE 15

Simultaneous Contrast Simultaneous Contrast

slide-16
SLIDE 16

Perceptual Distortions

  • Color-deficiency
  • Interactions between color components

– saturation - brightness (Helmholtz-Kohlraush effect) – brightness - hue (Bezold-Brucke Phenomenon)

  • Simultaneous contrast

– brightness – hue

  • Small field achrominance
  • Effects of color on perceived size

Small Field Achrominance

  • Wandell ‘95, cp. 3.
slide-17
SLIDE 17

Perceptual Distortions

  • Color-deficiency
  • Interactions between color components

– saturation - brightness (Helmholtz-Kohlraush effect) – brightness - hue (Bezold-Brucke Phenomenon)

  • Simultaneous contrast

– brightness – hue

  • Small field achrominance
  • Effects of color on perceived size

Color-size Illusion

  • Cleveland and McGill ‘83.
slide-18
SLIDE 18

Some Color Scales

  • Univariate

– color model component – optimal scales – double-ended

  • Multivariate

– color model components – Census Bureau TVCM – complementary display parameters

slide-19
SLIDE 19
slide-20
SLIDE 20

Some Color Scales

  • Univariate

– color model component – optimal scales – double-ended

  • Multivariate

– color model components – Census Bureau TVCM – complementary display parameters

slide-21
SLIDE 21

Some Color Scales

  • Univariate

– color model component – optimal scales – double-ended

  • Multivariate

– color model components – Census Bureau TVCM – complementary display parameters

  • Olson ‘97, fig. 11-8.
slide-22
SLIDE 22

Some Color Scales

  • Univariate

– color model component – optimal scales – double-ended

  • Multivariate

– color model components – Census Bureau TVCM – complementary display parameters

slide-23
SLIDE 23

Some Color Scales

  • Univariate

– color model component – optimal scales – double-ended

  • Multivariate

– color model components – Census Bureau TVCM – complementary display parameters

  • Tufte ‘83, pg. 153.
slide-24
SLIDE 24

Some Color Scales

  • Univariate

– color model component – optimal scales – double-ended

  • Multivariate

– color model components – Census Bureau TVCM – complementary display parameters

slide-25
SLIDE 25

Evaluating Color Scales

  • Trumbo’s Principles

– Order: ordered values should be represented by

  • rdered colors

– Separation: significantly different levels should be represented by distinguishable colors – Rows and columns: to preserve univariate information, display parameters should not obscure

  • ne another

– Diagonal: to show positive association, displayed colors should group into three perceptual classes: diagonal, above, below

slide-26
SLIDE 26
slide-27
SLIDE 27

Evaluating Color Scales

  • Trumbo’s Principles

– Order: ordered values should be represented by

  • rdered colors

– Separation: significantly different levels should be represented by distinguishable colors – Rows and columns: to preserve univariate information, display parameters should not obscure

  • ne another

– Diagonal: to show positive association, displayed colors should group into three perceptual classes: diagonal, above, below

slide-28
SLIDE 28

Evaluating Color Scales

  • Trumbo’s Principles

– Order: ordered values should be represented by

  • rdered colors

– Separation: significantly different levels should be represented by distinguishable colors – Rows and columns: to preserve univariate information, display parameters should not obscure

  • ne another

– Diagonal: to show positive association, displayed colors should group into three perceptual classes: diagonal, above, below

slide-29
SLIDE 29
  • Tufte ‘83, pg. 153.
slide-30
SLIDE 30

Evaluating Color Scales

  • Trumbo’s Principles

– Order: ordered values should be represented by

  • rdered colors

– Separation: significantly different levels should be represented by distinguishable colors – Rows and columns: to preserve univariate information, display parameters should not obscure

  • ne another

– Diagonal: to show positive association, displayed colors should group into three perceptual classes: diagonal, above, below

slide-31
SLIDE 31

Evaluating Color Scales (cont.)

  • Ware’s experiments

– metric (quantitative) judgements – surface (qualititative) judgements – redundant color scales

slide-32
SLIDE 32
  • Tufte ‘97, pg. 77.
  • Tufte ‘97, pg. 76.
slide-33
SLIDE 33

Ware’s Color Scales

  • Ware ‘88.
slide-34
SLIDE 34
slide-35
SLIDE 35

Considerations

  • Consider goals
  • Consider data
  • Consider audience
  • Consider color connotations
slide-36
SLIDE 36

Final Consideration

  • Does this work?
slide-37
SLIDE 37

Principles of Color Representation

  • Avoid distortions
  • Exploit the familiar
  • Emphasize the interesting
  • Say it again (redundant mappings)
  • Select appropriate level of detail
slide-38
SLIDE 38

Color Models: Device-derived

White Blue Cyan Red Yellow Magenta Green Black

  • Red-Green-Blue
slide-39
SLIDE 39

Color Models: Intuitive

Black White Red Yellow Green Cyan Blue Magenta V = 0 V = 1 Hue = 0 S = 0 S = 1 Hue

Black White Red Yellow Green Cyan Blue Magenta L = 0 L = 1 Hue = 0 S = 0 S = 1 Hue

  • Hue-Saturation-Value
  • Hue-Lightness-Saturation

Color Models: Perceptually Uniform

White Purple Purplish red Reddish purple Bluish green Greenish blue Blue Green Pink Purplish pink Red Reddish orange Yellowish green Yellow green Orange Yellow Purplish blue Orange Yellow Greenish Yellow Yellowish pink

u'

.100 .200 .300 .400 .500 .600 .700 .000 .100 .200 .300 .400 .500

v'

  • CIELUV
slide-40
SLIDE 40

Opponent Channel Recoding

Long (R) Medium (G) Short (B)

+

  • R - G

Y-B Achromatic Yellow