Friday, June 20, 2008

Colours of light by 2E3 Neo Chin Yen

In this topic, I get to learn the combination and recombination of rainbow colours, and how the colours are being produced, and the effects of mixing all primary colours. I also learnt that colour is a function of the human visual system, and is not an intrinsic property.

Objects don't "have" color, they give off light that "appears" to be a color. Spectral power distributions exist in the physical world, but color exists only in the mind of the beholder.

Color is the perceptual quality of light.

The color of the light coming from an object has its origin in one or more of the following processes …
emission: the object itself is a source of light with a color determined by its spectra

reflection: certain frequencies are reflected from the object while others are not

transmission: certain frequencies are transmitted through the object while others are not

interference: certain frequencies are amplified by constructive interference while others are attenuated by destructive interference

dispersion: the angular separation of a polychromatic light wave by frequency during refraction

scattering: the preferential reradiation of certain frequencies of light striking small, dispersed particles

Something interesting I want to share are some historical junks.
The painter's color wheel is a historical artifact that refuses to die. The primary colors are not red, yellow, and blue. Painters and art teachers promote this scheme. It is a convenient way to understand how to mimic one color by mixing red, yellow, and blue. But these colors do not satisfy the definition of primary colors in that they can't reproduce the widest variety of colors when combined.

Cyan, magenta, and yellow have a greater chromatic range as evidenced by their ability to produce a reasonable black. No combination of red, yellow, and blue pigments will approach black as closely as do cyan, magenta, and yellow.

The website I got all my informations are from www.hypertextbook.com/physics/

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