Colours

Specifying a colour by value

Hexadecimal RGB color values

The format of an RGB value in hexadecimal notation is a # immediately followed by either three or six hexadecimal characters. A general colour is specified in terms of the three primary colours red, blue and green. Each primary colour is defined as a one or two digit Hexadecimal number that representing the strength of that primary colour. The three-digit RGB notation (#rgb) is converted into six-digit form (#rrggbb) by replicating digits, not by adding zeros. For example, #fb0 expands to #ffbb00, and #fff expands to #ffffff

In this specification hexadecimal 00 means 0% of the colour and hexadecimal ff means 100% of the colour.

For example, to specify red the hexadecimal number #ff0000 is used. In this number:

• The first two digits after the # symbol ff define 100% of red
• The second two digits after the # symbol 00 define 0% of green
• The third two digits after the # symbol 00 define 0% of blue

* <span style="color:#ff0000;">Red</span>
* <span style="color:#00ff00;">Green</span>
* <span style="color:#0000ff;">Blue</span> *

* <span style="color:#ffff00;">Yellow</span>
* <span style="color:#00ffff;">Aqua</span>
* <span style="color:#ff00ff;">Purple</span> *

* <span style="color:#ffffff;">White</span>
* <span style="color:#000000;">Black</span> *

To convert an RGB color to its hexadecimal representation, you'll need to convert each of the Red, Green, and Blue components from decimal to hexadecimal and then combine them.

The formula to convert a decimal value to a two-digit hexadecimal value is often expressed as follows:

1. Divide the decimal value by 16 to get the quotient and remainder.
2. The remainder is the least significant digit (rightmost digit).
3. The quotient is the most significant digit (leftmost digit).
4. If the quotient or remainder is greater than 9, represent it using letters A-F (A for 10, B for 11, ..., F for 15).

Let's go through an example with the RGB color (135, 206, 250):

1. Red Component (135):
• Quotient: 135 ÷ 16 = 8 with a remainder of 7.
• The hexadecimal representation is 87.
2. Green Component (206):
• Quotient: 206 ÷ 16 = 12 with a remainder of 14.
• The hexadecimal representation is CE.
3. Blue Component (250):
• Quotient: 250 ÷ 16 = 15 with a remainder of 10.
• The hexadecimal representation is FA.

Combine these results, and you get the hexadecimal representation for the RGB color (135, 206, 250) as #87CEFA.

To convert Hexadecimal to Decimal, for example the #87CEFA:

• Red: 87 in hexadecimal is (8 * 16 + 7 * 1) = 135 in decimal.
• Green: CE in hexadecimal is (12 * 16 + 14 * 1) = 206 in decimal.
• Blue: FA in hexadecimal is (15 * 16 + 10 * 1) = 250 in decimal.

Hexadecimal color mixer

Experiment with the color mixer by changing the red, green and blue values using the corresponding sliders.