gek1532 introduction
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GEK1532: Color and Vision
Thorsten Wohland
Dep. Of Chemistry
S8-03-06
Tel.: 6516 1248
E-mail: chmwt@nus.edu.sg
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Goals of the course
Understanding of color
A) on a macroscopic level (example eye)
Basic understanding of how senses work
B) on a microscopic level (cell)
C) on a molecular level (proteins)
D) on a neurological level (brain)
E) on a psychological level (illusions)
F) on a philosophical level (implications)
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Organization
About 22 lectures and tutorials
Lecturer is on conference leave in the week ofFebruary 22
Midterm will be held on February 22 On Feb 25 a tutorial will be held
There will be 2 short quizzes (MCQ) as CA inclass
Discussion Forum (participation can lead toupgrading; no fixed percentage of mark)
Final will be MCQ (2/3) and questions (1/3)
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Start of lecture? Break?
When do we start? Are there any transport
problems?
Do you want a break?
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Some issues
Switch mobile phones off during lectures.
If you come late or go early do that
noiselessly. In the discussion forum stick to the topics.
Participate actively.
If you have questions: ASK!
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Books1. The physics and chemistry of color : the fifteen causes of color / Kurt Nassau.
2. Light science : physics and the visual arts / Thomas D. Rossing, Christopher Chiaverina.
3. Anatomy & physiology / Rod R. Seeley, Trent D. Stephens, Philip Tate.
4. Seeing the light : optics in nature, photography, color, vision, and holography / David S.
Falk, Dieter R. Brill, David G. Stork.
5. Color vision : perspectives from different disciplines / editors WernerG.K. Backhaus,Reinhold Kliegl, John S. Werner. Berlin ; New York : Walter de Gruyter, 1998
6. Light vision color / Arne Valberg.
7. Light and color in the outdoors / Marcel Minnaert ; translated and revised by Len Seymour.
8. Number by colors : a guide to using color to understand technical data / Brand Fortner,
Theodore E. Meyer.9. In the blink of an eye: how vision kick-started the big bang of evolution, Andrew parker
10. Thinks , David Lodge
11. Sensation and perception, 7th edition / E. Bruce Goldstein
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Websites
http://ivle.nus.edu.sg/
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Why is color useful?
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What is color?
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Is it a property of light?
http://www.geocities.com/Paris/Cinema/9080/various/sunday.html
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Is it a property of objects?
http://www.purveslab.net/seeforyourself/
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Is it a property of our brain?
How is it then possible that some people see color differently (color
deficient people), or do blind people know color?
http://www.allpsych.uni-giessen.de/karl/colbook/sharpe.pdf
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Is it a property determined by our
cultural background?Meaning of a color in different cultures, some examples:
China: luck
India: purity (in Western cultures purity is often blue)
Western: love
China: sacred, imperial (royalty in Western cultures is purple)
Western: cowardice, deceit, betrayal, jealousy, dishonesty
Germany: loyalty
US: depression
India: Color of Krishna
China: immortality, seriousness
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Is it a property determined by our
language?Color words in languages develop in a specific order and often reflect
the connections between colors.
Some languages have only the words for black/dark and
white/light: Dugerm Dani (New Guinea)
Some languages have words for all basic colors: Zuni (USA)
Some languages are in between these two extremes: Mandarin (China)
There is no generic word for orange, but the word is derived from the
fruit.
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Is it a property determined by our
language?
hue (horizontal axis) against lightness (vertical axis).
Nature 398, 203 - 204 (1999);
J. DAVIDOFF, I. DAVIES & D. ROBERSON
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Lets ask what is necessary to
perceive color Light as the medium that transfers information to us (lightsource)
An object which interacts with the light and changes itscharacteristics (wavelength, intensity) and is thus perceived
Eyes that act as a sensor for light (intensity and somewavelength discrimination)
The brain that interprets the signal detected by the eyesand leads to the perception of the color and object
It turns out that every single aspect here has an
influence on the color seen and color is not simply
characterized by any one of them alone!
http://tinyeyes.com/
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What are essential
properties of colors?
Saturation, hue, brightness
Spectral colors
Complementarity
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Newtons experiment
All these colors are said to have the
same hue but different saturation
(sometimes called chroma orpurity).
Colors obtained by passing white light
through a prism are the so-called
spectral hues or colors in the pure
spectrum.
More colors can be produced by mixing
these colors with white (ex.: red+white -
> pink).
http://physics.hallym.ac.kr
1643-1727: Newton used a prism to
decompose sunlight in its parts. He founded
a color theory and made the first color circle
to order colors.
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Spectral colors
400 nm 500 nm 600 nm 700 nm
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Some color fundamentals
Hue: This is the dominant saturated
color.
Brightness (luminous
intensity or luminous
emittance, shade):
Saturation (chroma or purity,
tint): The extend to which the
color is pure or has whitemixed in.
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Complementary Colors
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Complementary Colors
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Complementary Colors
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Red/Green
Complementary Colors in
Architecture
Blue/Yellow
Sky: blue
Grass: green
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How is color produced?
What are physical ways to produce color?
What are chemical reasons for color?
What are biological reasons for color?
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What are physical ways to produce
color?
Pictures from HyperPhysics by Rod Nave
Rainbows (refraction and
reflection)
The sun (color
temperature)
Blue sky (scattering)
Light: electromagnetic waves
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Chemical Reasons
562 nm
emission
~770 nm
emission
664 nm
emission
Dyes and pigments
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Biological color
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How is color classified?
http://www.colorsystem.com/projekte/Grafik/19max/01max.htm
L.C. Thomas, Fig. 3.7
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How is color perceived?
The role of the eye (lense) in producing images.
The retina and its color sensitive elements.
Nerve cells and their function and connections.
The role of the brain in color perception.
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The eye
http://webvision.med.utah.edu/
HyperPhysics by Rod Nave
Comparison to camera
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The retina and its color sensitive
elements.
Backhaus, Fig. 5.3
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The role of nerve cells and the
brain in color perception
http://web.mit.edu/rujira/www/4.206/neuron/synapse.html
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What are cultural and linguistic
determinants of color?
What are differences of color naming in different languages?
Are there general principles how languages develop color names?
How much influence has our cultural background on our color perception?
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Some questions to ponder
What is color?
Do different people see different colors? And is there an
objective way to find out?
What meaning has color in your culture?
Why is color important? Why did color perception evolve?
Has color acquired other meanings today?
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