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