Light
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Visible light is the portion of the electromagnetic spectrum that can be perceived by the human eye. It consists of the wavelengths ~400-500nm (blue light), ~500-600nm (green light), and ~600-700nm (red light). [1] When all these wavelengths are emitted at the same time it is considered white light, which can then be broken into it's constituent wavelengths by a prism via the process of refraction. This electromagnetic radiation is detected by the rods and cones in the eye and perceived as light.
[edit] Color
The human eye perceives color through cone cells in the eye. Three types of cones are sensitive to three different wavelengths that correspond with blue, green, and red light. [2] When white light reflects off of a "red" object, the green and blue wavelengths of light are absorbed, while the red wavelengths are reflected, the eye registers these wavelengths, and the brain interprets the result as "red." [3] This is known as subtractive color, and is the theory behind printed images. Projected images, such as those from a computer screen, follow the additive color theory. This theory states that red, green, and blue light mixed together produces white light. [4]
[edit] References
- ↑ John R. Jenson (2007). Remote Sensing of the Environment: An Earth Resource Perspective (2nd ed.). Pearson, 42. ISBN 0131889508
- ↑ http://hyperphysics.phy-astr.gsu.edu/hbase/vision/rodcone.html
- ↑ http://www.ux1.eiu.edu/~cfadd/1160/Ch23RR/Sub.html
- ↑ Judith A. Tyner (2010). Principles of Map Design. Guilford, 58. ISBN 9781606235447
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