8/6/2019 GEK1532 Introduction

1/35

GEK1532: Color and Vision

Thorsten Wohland

Dep. Of Chemistry

S8-03-06

Tel.: 6516 1248

E-mail: chmwt@nus.edu.sg

8/6/2019 GEK1532 Introduction

2/35

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)

8/6/2019 GEK1532 Introduction

3/35

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)

8/6/2019 GEK1532 Introduction

4/35

Start of lecture? Break?

When do we start? Are there any transport

problems?

Do you want a break?

8/6/2019 GEK1532 Introduction

5/35

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!

8/6/2019 GEK1532 Introduction

6/35

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

8/6/2019 GEK1532 Introduction

7/35

Websites

http://ivle.nus.edu.sg/

8/6/2019 GEK1532 Introduction

8/35

Why is color useful?

8/6/2019 GEK1532 Introduction

9/35

What is color?

8/6/2019 GEK1532 Introduction

10/35

Is it a property of light?

http://www.geocities.com/Paris/Cinema/9080/various/sunday.html

8/6/2019 GEK1532 Introduction

11/35

Is it a property of objects?

http://www.purveslab.net/seeforyourself/

8/6/2019 GEK1532 Introduction

12/35

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

8/6/2019 GEK1532 Introduction

13/35

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

8/6/2019 GEK1532 Introduction

14/35

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.

8/6/2019 GEK1532 Introduction

15/35

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

8/6/2019 GEK1532 Introduction

16/35

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/

8/6/2019 GEK1532 Introduction

17/35

What are essential

properties of colors?

Saturation, hue, brightness

Spectral colors

Complementarity

8/6/2019 GEK1532 Introduction

18/35

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.

8/6/2019 GEK1532 Introduction

19/35

Spectral colors

400 nm 500 nm 600 nm 700 nm

8/6/2019 GEK1532 Introduction

20/35

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.

8/6/2019 GEK1532 Introduction

21/35

Complementary Colors

8/6/2019 GEK1532 Introduction

22/35

Complementary Colors

8/6/2019 GEK1532 Introduction

23/35

Complementary Colors

8/6/2019 GEK1532 Introduction

24/35

Red/Green

Complementary Colors in

Architecture

Blue/Yellow

Sky: blue

Grass: green

8/6/2019 GEK1532 Introduction

25/35

How is color produced?

What are physical ways to produce color?

What are chemical reasons for color?

What are biological reasons for color?

8/6/2019 GEK1532 Introduction

26/35

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

8/6/2019 GEK1532 Introduction

27/35

Chemical Reasons

562 nm

emission

~770 nm

emission

664 nm

emission

Dyes and pigments

8/6/2019 GEK1532 Introduction

28/35

Biological color

8/6/2019 GEK1532 Introduction

29/35

How is color classified?

http://www.colorsystem.com/projekte/Grafik/19max/01max.htm

L.C. Thomas, Fig. 3.7

8/6/2019 GEK1532 Introduction

30/35

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.

8/6/2019 GEK1532 Introduction

31/35

The eye

http://webvision.med.utah.edu/

HyperPhysics by Rod Nave

Comparison to camera

8/6/2019 GEK1532 Introduction

32/35

The retina and its color sensitive

elements.

Backhaus, Fig. 5.3

8/6/2019 GEK1532 Introduction

33/35

The role of nerve cells and the

brain in color perception

http://web.mit.edu/rujira/www/4.206/neuron/synapse.html

8/6/2019 GEK1532 Introduction

34/35

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?

8/6/2019 GEK1532 Introduction

35/35

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?