Colour perception

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2.1 Color Perception PSYC 579 Topic Presentation, University of British Columbia Diliara Nasirova School of Interactive Art and Technology, Simon Fraser University January 26, 2011

description

Presentation on Colour Perception in Visual Perception theory and application course @PSYC UBC Spring 2011

Transcript of Colour perception

Page 1: Colour perception

2.1 Color Perception PSYC 579 Topic Presentation, University of British Columbia

Diliara Nasirova

School of Interactive Art and Technology, Simon Fraser University

January 26, 2011

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Outline

1.  The Physical Description of Light ■  Light Components ■  Electromagnetic Spectrum

2.  The Psychological Description of Color ■  Color Space

3.  Theories of Color Vision ■  Trichromatic Theory ■  Opponent Process Theory

Diliara Nasirova | PSYC 579 | Jan 26, 2011

4.  Basic Phenomena ■  Color Blindness ■  Color Afterimage ■  Color Contrast

5.  Application to Visual Design ■  Color Specification Interfaces ■  Color for Labeling

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References

1.  C. Ware, “Information Visualization: Perception for Design”, ch. 4 “Color” 2.  SE. Palmer, “Vision Science”

3.  E. Tufte, “Envisioning Information”, ch. 5 “Color and information” 4.  P Rheingans. (1999). “Task-based Color Scale Design” 5.  CA Brewer. (2005). “Designing Better Maps”, ch. 5 “Color Decisions for

Mapping”

6.  C. Ware, “Visual Thinking for Design”, ch. 4 “Color” 7.  M. Stone, “Color in Information Display” workshop, Vis08

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The Physical Description of Light Light Components

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•  Sir Isaac Newton, 1666

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The Physical Description of Light Electromagnetic Spectrum

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The Psychological Description of Color Color Space

•  All colors experiences can be described in terms of three dimensions: ■  Hue ■  Value (lightness) ■  Saturation (chroma)

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The Psychological Description of Color Color Space

•  Color space: ■  A three dimensional coordinate

system ■  Each color can be represented as a

single point with a unique position.

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The Psychological Description of Color Color Space

•  Color solid: Subset of color space

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Lightness

Hue

Saturation

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Theories of Color Vision Trichromatic Theory

•  Trichromacy: Three color receptors (cones) in retinas that are active at normal light levels

•  Young-Helmholtz Trichromatic Theory

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The Physical Description of Light Spectral Diagram

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•  Human cone sensitivity functions.

•  Cones sensitive to ■  S (blue) ■  M (green) ■  L (red)

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The Physical Description of Light Spectral Diagram: Short wavelength sensitive cones

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Blue text on a dark background is to be avoided. We have very few short-wavelength sensitive cones in the retina and they are not very sensitive.

Blue text on a dark background is to be avoided. We have very few short-wavelength sensitive cones in the retina and they are not very sensitive.

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The Physical Description of Light Spectral Diagram: Short wavelength sensitive cones

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Blue text on a dark background is to be avoided. We have very few short-wavelength sensitive cones in the retina and they are not very sensitive.

Blue text on a dark background is to be avoided. We have very few short-wavelength sensitive cones in the retina and they are not very sensitive.

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Theories of Color Vision Opponent Process Theory

•  Ewald Hering Opponent Process Theory

•  Six elementary colors arranged as opponent pairs along three axes: ■  black-white, ■  red-green, ■  yellow-blue.

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Theories of Color Vision Opponent Process Theory: Physiological basis

•  Input from the cones is processed into 3 distinct channels

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Theories of Color Vision Opponent Process Theory: Scientific evidence

1.  Unique Hues: black, white, red, green…

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Theories of Color Vision Opponent Process Theory: Scientific evidence

2.  Naming and Cross-Cultural Naming:

“yellowish green”, but no “yellowish blue”

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3.  Neurophysiology: cells in visual cortexes of monkeys that have properties of opponency

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Theories of Color Vision Opponent Process Theory: Scientific evidence

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3.  Categorical Colors:

■  Evidence that confusion between colors is affected by color categories

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Theories of Color Vision Opponent Process Theory: Scientific evidence

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Theories of Color Vision Opponent Process Theory: Scientific evidence

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Theories of Color Vision Opponent Process Theory: Color Channels Properties

•  Chromatic channels carry ~1/3 the amount of detail carried by the black–white channel.

•  Difficult to read the text where luminance is equal, despite a large chromatic difference

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Theories of Color Vision Opponent Process Theory: Color Channels Properties

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•  Form: Form perception processed mainly through the luminance channel

Floor, Duomo di Siena

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Theories of Color Vision Opponent Process Theory: Color Channels Properties

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•  Form: Pseudocolor sequences for maps

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Basic Phenomena Color Contrast

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•  Colors are perceived relative to their overall context

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Basic Phenomena Color Blindness

•  ~10% of the male and ~1% of the female population have some form of color vision deficiency.

Original

Deuteranope (r/g)

Protanope (r/g)

Tritanope (y/b)

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Basic Phenomena Color Blindness

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Basic Phenomena Color Blindness

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Normal vision: no number Color blind vision: “45”

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Basic Phenomena Color Afterimage

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Basic Phenomena Color Afterimage

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.

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Basic Phenomena Color Afterimage

•  BMW commercial: http://www.huffingtonpost.com/2010/12/16/bmw-ad-vide-burns-logo-into-eyes-_n_797981.html

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Application to Visual Design Color Specification Interfaces

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•  One of the most widely used color interfaces in computer graphics is based on the HSV color space

saturation

hue value

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Application to Visual Design Color Specification Interfaces

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Application to Visual Design Color for Labeling

•  Labeling: nominal information coding

•  Color can be extremely effective as a nominal code.

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Application to Visual Design Color for Labeling

•  Perceptual factors to be considered: 1.  Distinctness 2.  Unique hues 3.  Contrast with background 4.  Color blindness 5.  Number 6.  Field size 7.  Conventions

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Application to Visual Design Color for Labeling

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•  Perceptual factors to be considered: 1.  Distinctness 2.  Unique hues 3.  Contrast with background 4.  Color blindness 5.  Number 6.  Field size 7.  Conventions

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Application to Visual Design Color for Labeling

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•  Perceptual factors to be considered: 1.  Distinctness 2.  Unique hues 3.  Contrast with background 4.  Color blindness 5.  Number 6.  Field size 7.  Conventions

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Application to Visual Design Color for Labeling

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•  Perceptual factors to be considered: 1.  Distinctness 2.  Unique hues 3.  Contrast with background 4.  Color blindness 5.  Number 6.  Field size 7.  Conventions

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Application to Visual Design Color for Labeling

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•  Perceptual factors to be considered: 1.  Distinctness 2.  Unique hues 3.  Contrast with background 4.  Color blindness 5.  Number 6.  Field size 7.  Conventions

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Application to Visual Design Color for Labeling

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•  Perceptual factors to be considered: 1.  Distinctness 2.  Unique hues 3.  Contrast with background 4.  Color blindness 5.  Number 6.  Field size 7.  Conventions

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Application to Visual Design Color for Labeling

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•  Perceptual factors to be considered: 1.  Distinctness 2.  Unique hues 3.  Contrast with background 4.  Color blindness 5.  Number 6.  Field size 7.  Conventions

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Application to Visual Design Color for Labeling

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•  12 colors recommended for use in coding.

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Conclusion