Colour value

Colour values are the sets of numbers and/or characters used by colour models to systematically identify and store colour information in a form of colour notation recognisable to both computers and humans. Every colour within a colour model is assigned its own unique colour value.

The RGB colour model uses both decimal and hexadecimal triplets for colour notation. Each of the three components within a triplet contains a value corresponding to red, green or blue. The colour values within RGB triplets appear as follows:

  • Decimal notation for orange: R=255, G=128, B=0.
  • Hexadecimal RGB notation for orange: #FF8000.

The HSB colour model uses decimal triplets for colour notation. Each of the three components within a triplet contains a value corresponding to hue, saturation or brightness. The colour values within HSB triplets appear as follows:

  • Decimal notation for orange: H=30.12, S=100, B=100.

The CMYK colour model uses decimal quadruplets for colour notation. Each of the four components within a quadruplet contains a value corresponding to cyan, magenta, yellow or black. The colour values within CMYK quadruplets appear as follows:

  • Decimal notation for orange: C=0, M=61.48, Y=100, K=0.

Summary

RGB colour notation

RGB colour values are expressed as decimal triplets (yellow = 255, 255, 0) or hexadecimal triplets (green = #00FF00). Computer software is programmed to recognise RGB colour values.

In both cases, the triplets determine the amount of red, green and blue used to produce a specific colour.
A decimal triplet is made up of three numbers between 0 and 255 divided by commas.
A hexadecimal triplet starts with a # sign followed by three two-digit numbers with values between  00 and FF written without spaces between.

RGB colour values are based on decimal notation (triplets with a base 10) or hexadecimal notation (triplets with a base 16).

  • Decimal notation uses 10 digits from 0 to 9 as follows, 0, 1, 2, 3, 4, 5, 6, 7, 8 and 9.
  • The hexadecimal notation uses 16 digits from 0 to F as follows, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C, D, E and F.
  • Hexadecimal notation for values between 16 and 31 are as follows 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 1A, 1B, 1C, 1D, 1E and 1F.
RGB decimal notation
  • In decimal notation, an RGB triplet is used to represent the values of red, then green, then blue. A range of decimal numbers between 0 to 255 can be selected for each value.
    • Red = 255, 0, 0
    • Yellow = 255, 255, 0
    • Green = 0, 255, 0
    • Cyan = 0, 255, 255
    • Blue = 0, 0, 255
    • Magenta = 255, 0, 255
RGB hexadecimal notation
  • In hexadecimal notation an RGB triplet is used to represent the value of red, then green, then blue. A range of  hexadecimal numbers from 00 to FF can be selected for each value.
  • The hash symbol (#) is used to indicate hex notation.
    • Red = #FF0000
    • Yellow = #FFFF00
    • Green = #00FF00
    • Cyan = #00FFFF
    • Blue = #0000FF
    • Magenta = #FF00FF