Colour perception
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Transcript of 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
Diliara Nasirova | PSYC 579 | Jan 26, 2011
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The Physical Description of Light Light Components
Diliara Nasirova | PSYC 579 | Jan 26, 2011
• Sir Isaac Newton, 1666
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The Physical Description of Light Electromagnetic Spectrum
Diliara Nasirova | PSYC 579 | Jan 26, 2011
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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)
Diliara Nasirova | PSYC 579 | Jan 26, 2011
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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
Diliara Nasirova | PSYC 579 | Jan 26, 2011
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
Diliara Nasirova | PSYC 579 | Jan 26, 2011
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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
Diliara Nasirova | PSYC 579 | Jan 26, 2011
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
Diliara Nasirova | PSYC 579 | Jan 26, 2011
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.
Diliara Nasirova | PSYC 579 | Jan 26, 2011
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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…
Diliara Nasirova | PSYC 579 | Jan 26, 2011
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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
Diliara Nasirova | PSYC 579 | Jan 26, 2011
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
Diliara Nasirova | PSYC 579 | Jan 26, 2011
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
Diliara Nasirova | PSYC 579 | Jan 26, 2011
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Theories of Color Vision Opponent Process Theory: Color Channels Properties
Diliara Nasirova | PSYC 579 | Jan 26, 2011
• 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
Diliara Nasirova | PSYC 579 | Jan 26, 2011
• Form: Pseudocolor sequences for maps
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Basic Phenomena Color Contrast
Diliara Nasirova | PSYC 579 | Jan 26, 2011
• 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
Diliara Nasirova | PSYC 579 | Jan 26, 2011
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Basic Phenomena Color Blindness
Diliara Nasirova | PSYC 579 | Jan 26, 2011
Normal vision: no number Color blind vision: “45”
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Basic Phenomena Color Afterimage
Diliara Nasirova | PSYC 579 | Jan 26, 2011
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Basic Phenomena Color Afterimage
Diliara Nasirova | PSYC 579 | Jan 26, 2011
.
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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
Diliara Nasirova | PSYC 579 | Jan 26, 2011
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Application to Visual Design Color Specification Interfaces
Diliara Nasirova | PSYC 579 | Jan 26, 2011
• 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
Diliara Nasirova | PSYC 579 | Jan 26, 2011
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Application to Visual Design Color for Labeling
• Labeling: nominal information coding
• Color can be extremely effective as a nominal code.
Diliara Nasirova | PSYC 579 | Jan 26, 2011
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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
Diliara Nasirova | PSYC 579 | Jan 26, 2011
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Application to Visual Design Color for Labeling
Diliara Nasirova | PSYC 579 | Jan 26, 2011
• 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
Diliara Nasirova | PSYC 579 | Jan 26, 2011
• 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
Diliara Nasirova | PSYC 579 | Jan 26, 2011
• 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
Diliara Nasirova | PSYC 579 | Jan 26, 2011
• 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
Diliara Nasirova | PSYC 579 | Jan 26, 2011
• 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
Diliara Nasirova | PSYC 579 | Jan 26, 2011
• 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
Diliara Nasirova | PSYC 579 | Jan 26, 2011
• 12 colors recommended for use in coding.
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Conclusion