Color code

A color code is a system for encoding and representing non-color information with colors to facilitate communication. This information tends to be categorical (representing unordered/qualitative categories) though may also be sequential (representing an ordered/quantitative variable).

History

The earliest examples of color codes in use are for long-distance communication by use of flags, as in semaphore communication.^[1] The United Kingdom adopted a color code scheme for such communication wherein red signified danger and white signified safety, with other colors having similar assignments of meaning.

As chemistry and other technologies advanced, it became expedient to use coloration as a signal for telling apart things that would otherwise be confusingly similar, such as wiring in electrical and electronic devices, and pharmaceutical pills.

Encoded Variable

A color code encodes a variable, which may have different representations, where the color code type should match the variable type:

Categorical variable - the variable may represent discrete values of unordered qualitative data (e.g. race)
- Binary variables are typically treated as a categorical variable (e.g. sex)
Quantitative variable - the variable represents ordered, quantitative data (e.g. age)
- Discrete quantitative data (e.g. the 6 sides of a die: 1,2,3,4,5,6) are sometimes treated as a categorical variable, despite the ordered nature.

Types

The types of color code are:

Categorical - the colors are unordered, but are chosen to maximize saliency of the colors, by maximizing color difference between all color pair permutations.
Continuous - the colors are ordered and form a smooth color gradient.
Discrete - only a subset of a continuous color code are used (still ordered), where each is distinguishable from the others.

Criticism

Color codes present some potential problems. On forms and signage, the use of color can distract from black and white text.^[2]

Color codes are often designed without consideration for accessibility to color blind and blind people, and may even be inaccessible for those with normal color vision, since use of many colors to code many variables can lead to use of confusingly similar colors.^[2]

Examples

Systems incorporating color-coding include:

In electricity:
- 25-pair color code – telecommunications wiring
- Audio connectors
- Video connectors
- Optical fibers
- Electrical wiring – AC power phase, neutral, and grounding wires
- Electronic color code AKA resistor or EIA color code (today - IEC 60062:2016 )
- Ethernet twisted-pair wiring – local area networks
- Jumper cables used to jump-start a vehicle
- PC99 connectors and ports
- Surround sound ports and cables
- Three-phase electric power (electrical wiring)
In video games
- Health and magic points
- To distinguish friend from foe, for instance in StarCraft, Halo, or League of Legends
- To distinguish rarity or quality of items in adventure and role-playing games^[3]
In navigation:
Other technology:
- At point of sale (especially for packaging within a huge range of products: to quickly differentiate variants, brands, categories)
- Bottled gases
- Fire extinguishers
- Kerbside collection
- Pipe marking
- Queen bee birth year code
- Underground utility location
- Hospital emergency codes often incorporate colors (such as the widely used "Code Blue" indicating a cardiac arrest),
In military use:
- Homeland Security Advisory System
- Artillery shells and other munitions, which are color-coded according to their pyrotechnic contents
- List of Rainbow Codes
- NATO Military Symbols for Land Based Systems
- Rainbow Herbicides
In social functions:
- Black hat hacking, white hat, grey hat
- Blue-collar worker, white-collar worker, pink-collar worker, grey-collar, green-collar worker
- Handkerchief code
- ISO 22324, Guidelines for color-coded alerts in public warning
- Cooper's Color Code of the combat mindset
- Rank in Judo
- Ribbon colors see: Category:Ribbon symbolism
In religion:
- Clerical vestments, frontals and altar hangings in Christian churches

References

^ Transactions of the American Society of Civil Engineers: Volume 29 (1893), p. 507.
^ ^a ^b See, e.g., Michael Richard Cohen, Medication Errors (2007), p. 119.
^ "Color-Coded Loot". Giant Bomb. Retrieved 13 June 2016.

External links

Media related to Color code at Wikimedia Commons

[1] Transactions of the American Society of Civil Engineers: Volume 29 (1893), p. 507.

[Cohen-2] See, e.g., Michael Richard Cohen, Medication Errors (2007), p. 119.

[3] "Color-Coded Loot". Giant Bomb. Retrieved 13 June 2016.

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