Color

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Introduction

Color can be approached from different perspectives including natural sciences, color theory, technology, philosophy, biology, medicine, psychology, human factors engineering, arts. Color is not a property of objects, spaces or surfaces, but it is the sensation caused by certain qualities of light recognized by the eye and interpreted by the brain. Therefore light and color are inseparable. They affect body functions and influence the mind and emotions.


The electromagnetic spectrum


Physically, light is electromagnetic energy which travels in waves. The wavelength is measured in Angstrom units or nanometers. Only a narrow range of this energy is visible to humans, while ultraviolet light, x-rays, TV and radiowaves cannot be seen. Visible light ranges from a wavelength region of approximately 380 nanometers (equivalent to violet) to a region of 780 nanometers (equivalent to red).


Colors can be distinguished from one another by three attributes: hue, saturation and lightness (or value). Hue is physically determined by wavelength, elementary hues are red, orange, yellow, green, blue and violet.


Changing hue.jpg


Saturation refers to the dominant hue (wavelength) and its ratio to the other wavelengths in a color. It can also be described as the purity, strength or intensity of a color. White light contains an even balance of all wavelengths.


Changing saturation.jpg


Lightness defines how much light is reflected from a surface, it describes the difference between dark and light.


Changing lightness.jpg


The term “Color temperature” is often used to describe the color appearance of a light source, as being either warm or cool. Warm refers to yellowish or peach colored light, cool refers to bluish light. The color temperature is expressed in kelvins (K) beginning with absolute zero. The higher the color temperature the cooler the light appears (10.000K = blue-white light, 5300K = noon sunlight, 1800K = candlelight).

Section Key Resources
  • Mahnke, F.H. (1996): Colour, Environment and Human Response, Van Nostrand Reinhold, New York, USA
  • Church, A.H. (2008): Colour, and elementary manual for students, googlebooks
  • Illuminating Engineering Society of North America (xxxx): Light+Design, A Guide to Designing Quality Lighting for People and Buildings, IES DG-18-08
  • Illuminating Engineering Society of North America (2000): The IESNA Lighting Handbook, Reference and Application, Ninth edition, IESNA, New York, USA
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Lead Author(s): Aris Tsangrassoulis

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