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## Science Fair Project Encyclopedia for Schools!

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# Science Fair Project Encyclopedia

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# Grey

Grey or gray is a color seen commonly in nature. It is created by mixing white and black in different proportions. Depending on the amount of light, the human eye can interpret the same object as either grey or some other color.

Two colors are called complementary colors if grey is produced when lights of the two colors are combined. The psychological primary colors are:

Other sets of complementary colors include:

Grey is its own complement. In an afterimage, which can be seen after seeing the picture for about 30 seconds, the colors will switch to their complements.

## Usage, symbolism and colloquial expressions

• "Grey life", meaning mere existence without much sense or goal.
• A "grey person" is someone who goes unnoticed, a wallflower.
• Grey was used as the color of the uniforms of Confederate soldiers during the American Civil War, as opposed to the blue uniforms of Union soldiers.
• In a moral sense grey is either used
• pejoratively to describe situations that have no clear moral value, or
• positively to balance an all-black or all-white view (for example, shades of grey = magnitudes of good/bad)
• Grey has been used to describe the industrialism, as opposed to green to describe environmentalism.
• The hair becomes grey as one ages, and hence grey is associated with senior citizens, and has inspired the name of the Gray Panthers.
• The substance that composes the brain is referred to as "grey matter", and for that reason the color is associated with things intellectual. "Theory is grey... "

## Color coordinates

RGB
All the grey values in greyscale are solutions of the inequality:
$0 \le ( R = G = B ) \le 255$
CMYK
All the grey values in greyscale are solutions of the inequality:
$0 \le K \le 255$ when $C = M = Y = 0 \,$.
In theory it is also possible to achieve a greyscale with perfect inks when:
$C = M = Y \,$ and $K = 0 \,$
HSV
All the grey values in greyscale are solutions of the inequality:
$0 \le V \le 100$ when $H = S = 0 \,$ .