RationalWiki:Help/Color

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Color (colour to our transatlantic cousins) on computer screens is made up of 3 "primary" colors: red, green and blue.
You will often see this referred to as "RGB", these colors are "additive": zero of all three gives black, while maximum of all three makes white.^[1]

Contents 1 Colors by number 2 Colors by name 3 Text color coding 4 Other use of colors 5 Examples to copy 6 Notes

[edit] Colors by number

Computers work with powers of two. The relevant vocabulary for describing colors uses "hexadecimal", which is base sixteen.^[2]

• 0 (zero) to 15 (which is 16 or 2⁴ higher), using one hex digit for each base color, for a total of 16³, or 4,096 values.
• 0 (Zero) to 255 (which is 256 or 2⁸ higher), using two hex digits for each color, yielding a total of 256³, or 16,777,216 values;
  Each base color (red, green, and blue) can have a value in one of these ranges.

Hexadecimal color codes are preceded by "#".

Using the 0-15 method, a RGB color is represented as #000 for black, through #FFF for white.

In the 0-255 method, black is #000000 and white is #FFFFFF.

Note that equal amounts of red, green and blue produce various shades of gray. Pure reds are of the form #XX0000, greens are #00XX00, and pure blue shades are #0000XX. Any color combination can be created using any number from 00 to FF in each of the three positions.

[edit] Colors by name

There are also palettes of named colors.

Color name	Hexadecimal		Color name	Hexadecimal		Color name	Hexadecimal		Color name	Hexadecimal
	Background	Text		Background	Text		Background	Text		Background	Text
aqua	#00FFFF	Sample text on black	black	#000000	Sample text	blue	#0000FF	Sample text	fuchsia	#FF00FF	Sample text
gray	#808080	Sample text	green	#008000	Sample text	lime	#00FF00	Sample text on black	maroon	#800000	Sample text
navy	#000080	Sample text	olive	#808000	Sample text	purple	#800080	Sample text	red	#FF0000	Sample text
silver	#C0C0C0	Sample text on black	teal	#008080	Sample text	white	#FFFFFF	Sample text on black	yellow	#FFFF00	Sample text on black

There is another palette of named colors which might or might not work with various web browsers. (These colors are now generally functional on all browsers; see here).

[edit] Text color coding

Text colors are commonly manipulated with the "font" tag:

• <font color="red">RED TEXT</font>
  • RED TEXT
• <font color="#0F0">GREEN TEXT</font>
  • GREEN TEXT
• <font color="#0000FF">BLUE TEXT</font>
  • BLUE TEXT

Note, the above method is old HTML and, although it will work for as long as this wiki is alive(?) it has been replaced by new HTML:

<span style="color:hex triplet or colour name">text</span>

• <span style="color:red">red writing</span>
  • red writing
• <span style="color:#0F0">green writing</span>
  • green writing
• <span style="color:#0000FF">blue writing</span>
  • blue writing

This has the advantage that other attributes can be included in the same "span" tag.^[3]

[edit] Other use of colors

Colors can also be defined in other html tags, such as table tags. BGCOLOR="#abcxyz" will set the background color of a table, row, or cell when used inside the appropriate tag. Wiki table colors can also be defined using the "style" attribute.

[edit] Examples to copy

As with many tricks and tools on computers, copying something you like is often the quickest way to get there.

[edit] Notes

1. ↑ In printing, four colours are used: cyan, magenta, yellow and black (alright black's not really a color but that's the way it goes) referred to as "CMYK"; these are "subtractive": zero of all four gives white while maximum of all four (or maximum of all 3 colors, or just maximum of black) gives black)
2. ↑ Hexadecimal numbers are how geeks count up to 16 (0 -15 actually) without using more than one digit. Count in hexadecimal: 0,1,2,3,4,5,6,7,8,9,A,B,C,D,E,F.
3. ↑ You might like to follow up by reading about Cascading Style Sheets in Wikipedia.

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