Web colors are colors used in designing web pages, and the methods for describing and specifying those colors.

Authors of web pages have a variety of options available for specifying colors for elements of web documents. Colors may be specified as an RGB triplet in hexadecimal format (a hex triplet); they may also be specified according to their common English names in some cases. Often a color tool or other graphics software is used to generate color values.

The first versions of Mosaic and Netscape Navigator used the X11 color names as the basis for their color lists, as both started as X Window System applications. The origin of the X11 color list is unknown. ^*

Web colors have an unambiguous colorimetric definition, sRGB, which relates the chromaticities of a particular phosphor set, a given transfer curve, adaptive whitepoint, and viewing conditions. These have been chosen to be similar to many real-world monitors and viewing conditions, so that even without color management rendering is fairly close to the specified values. However, user agents vary in the fidelity with which they represent the specified colors. More advanced user agents use color management to provide better color fidelity; this is particularly important for Web to print applications.

Hex triplet

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A hex triplet is a six-digit, three-byte hexadecimal number used in HTML and CSS, and other computing applications, to represent colors. The bytes represent the red, green and blue components of the color. One byte represents a number in the range 00 to FF (in hexadecimal notation), or 0 to 255 in decimal notation. This represents the least (0) to the most (255) intensity of each of the color components. The hex triplet is formed by concatenating three bytes in hexadecimal notation, in the following order:

Byte 1: red value

Byte 2: green value

Byte 3: blue value

For example, consider the color where the red/green/blue values are decimal numbers: red=36, green=104, blue=160 (a greyish-blue color). The decimal numbers 36, 104 and 160 are 24, 68 and A0 respectively in hexadecimal notation. To obtain the hex triplet, we simply write the three hex bytes together without spaces, thus: 2468A0. If a byte is less than 16 (decimal) or 10 (hex) it must be represented with a leading zero to keep the number of digits in the triplet equal to six. For example, the decimal triplet 0,1,2 would be represented by the hex triplet 000102.

The number of colors that can be represented by this system is

$256\; \backslash times\; 256\; \backslash times\; 256\; =\; 16,777,216$

Converting RGB to hexadecimal

Converting a decimal RGB value to a hexadecimal value is fairly straightforward. RGB values are usually given in the 0-255 range; if they are in the 0-1 range, multiply the value by 255 before conversion. The number of times this number divides into 16 gives us the first hexadecimal digit (between 0 and F, see hexadecimal if unsure). The remainder gives us the second digit. For instance the RGB value 201 divides 12 times into 16, thus the first digit is C. A remainder of 9 gives us the hexadecimal number C9. This process is repeated for each color value. Most modern operating systems have a built-in calculator to perform conversions between number bases; this can also be done with some calculators. This task can also be carried out with various Internet resources, for instance the website http://www.telacommunications.com/nutshell/rgbform.htm.

HTML color names

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The HTML 4.01 specificationHTML 4.01 Specification section 6.5 "Colors" defines sixteen named colors, as follows (names are defined in this context to be case independent):

Color	Hexadecimal	Color	Hexadecimal	Color	Hexadecimal	Color	Hexadecimal
aqua	#00ffff	black	#000000	blue	#0000ff	fuchsia	#ff00ff
gray	#808080	green	#008000	lime	#00ff00	maroon	#800000
navy	#000080	olive	#808000	purple	#800080	red	#ff0000
silver	#c0c0c0	teal	#008080	white	#ffffff	yellow	#ffff00

These 16 were also specified as sRGB and included in the HTML 3.0 specification which noted "These colors were originally picked as being the standard 16 colors supported with the Windows VGA palette." HTML 3.2 Specification "The BODY element"

X11 color names

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In addition, a number of colors are defined by web browsers such as Internet Explorer or Mozilla Firefox. A particular browser may not recognize all of these colors, but as of 2005 all modern general-use browsers support the full list. Many of these colors are from the list of X11 color names distributed with the X Window System. These colors were standardized by SVG 1.0, and are accepted by SVG Full user agents. They are not part of SVG Tiny.

The list of colors actually shipped with the X11 product varies between implementations, and clashes with certain of the HTML names such as green. Furthermore, X11 colors are defined as simple RGB (hence, no particular color), rather than sRGB. This means that the list of colors found in X11 (e.g. in /usr/lib/X11/rgb.txt) should not directly be used to choose colors for the web.Public discussion on SVG mailing list Re: color names in SVG-1.0 conflict with /usr/lib/X11/rgb.txt

The list of web "X11 colors" from the CSS3 specification, along with their hexadecimal equivalents, is shown below, compare the alphabetical lists in the W3C standards. W3C TR CSS3 Color Module, SVG color keywords W3C TR SVG 1.0, recognized color keyword names

HTML name	Hex code R   G   B
Red colors
IndianRed	CD 5C 5C
LightCoral	F0 80 80
Salmon	FA 80 72
DarkSalmon	E9 96 7A
LightSalmon	FF A0 7A
Crimson	DC 14 3C
Red	FF 00 00
FireBrick	B2 22 22
DarkRed	8B 00 00
Pink colors
Pink	FF C0 CB
LightPink	FF B6 C1
HotPink	FF 69 B4
DeepPink	FF 14 93
MediumVioletRed	C7 15 85
PaleVioletRed	DB 70 93
Orange colors
LightSalmon	FF A0 7A
Coral	FF 7F 50
Tomato	FF 63 47
OrangeRed	FF 45 00
DarkOrange	FF 8C 00
Orange	FF A5 00
Yellow colors
Gold	FF D7 00
Yellow	FF FF 00
LightYellow	FF FF E0
LemonChiffon	FF FA CD
LightGoldenrodYellow	FA FA D2
PapayaWhip	FF EF D5
Moccasin	FF E4 B5
PeachPuff	FF DA B9
PaleGoldenrod	EE E8 AA
Khaki	F0 E6 8C
DarkKhaki	BD B7 6B
Purple colors
Lavender	E6 E6 FA
Thistle	D8 BF D8
Plum	DD A0 DD
Violet	EE 82 EE
Orchid	DA 70 D6
Fuchsia	FF 00 FF
Magenta	FF 00 FF
MediumOrchid	BA 55 D3
MediumPurple	93 70 DB
BlueViolet	8A 2B E2
DarkViolet	94 00 D3
DarkOrchid	99 32 CC
DarkMagenta	8B 00 8B
Purple	80 00 80
Indigo	4B 00 82
SlateBlue	6A 5A CD
DarkSlateBlue	48 3D 8B

HTML name	Hex code R   G   B
Green colors
GreenYellow	AD FF 2F
Chartreuse	7F FF 00
LawnGreen	7C FC 00
Lime	00 FF 00
LimeGreen	32 CD 32
PaleGreen	98 FB 98
LightGreen	90 EE 90
MediumSpringGreen	00 FA 9A
SpringGreen	00 FF 7F
MediumSeaGreen	3C B3 71
SeaGreen	2E 8B 57
ForestGreen	22 8B 22
Green	00 80 00
DarkGreen	00 64 00
YellowGreen	9A CD 32
OliveDrab	6B 8E 23
Olive	80 80 00
DarkOliveGreen	55 6B 2F
MediumAquamarine	66 CD AA
DarkSeaGreen	8F BC 8F
LightSeaGreen	20 B2 AA
DarkCyan	00 8B 8B
Teal	00 80 80
Blue colors
Aqua	00 FF FF
Cyan	00 FF FF
LightCyan	E0 FF FF
PaleTurquoise	AF EE EE
Aquamarine	7F FF D4
Turquoise	40 E0 D0
MediumTurquoise	48 D1 CC
DarkTurquoise	00 CE D1
CadetBlue	5F 9E A0
SteelBlue	46 82 B4
LightSteelBlue	B0 C4 DE
PowderBlue	B0 E0 E6
LightBlue	AD D8 E6
SkyBlue	87 CE EB
LightSkyBlue	87 CE FA
DeepSkyBlue	00 BF FF
DodgerBlue	1E 90 FF
CornflowerBlue	64 95 ED
MediumSlateBlue	7B 68 EE
RoyalBlue	41 69 E1
Blue	00 00 FF
MediumBlue	00 00 CD
DarkBlue	00 00 8B
Navy	00 00 80
MidnightBlue	19 19 70

HTML name	Hex code R   G   B
Brown colors
Cornsilk	FF F8 DC
BlanchedAlmond	FF EB CD
Bisque	FF E4 C4
NavajoWhite	FF DE AD
Wheat	F5 DE B3
BurlyWood	DE B8 87
Tan	D2 B4 8C
RosyBrown	BC 8F 8F
SandyBrown	F4 A4 60
Goldenrod	DA A5 20
DarkGoldenrod	B8 86 0B
Peru	CD 85 3F
Chocolate	D2 69 1E
SaddleBrown	8B 45 13
Sienna	A0 52 2D
Brown	A5 2A 2A
Maroon	80 00 00
White colors
White	FF FF FF
Snow	FF FA FA
Honeydew	F0 FF F0
MintCream	F5 FF FA
Azure	F0 FF FF
AliceBlue	F0 F8 FF
GhostWhite	F8 F8 FF
WhiteSmoke	F5 F5 F5
Seashell	FF F5 EE
Beige	F5 F5 DC
OldLace	FD F5 E6
FloralWhite	FF FA F0
Ivory	FF FF F0
AntiqueWhite	FA EB D7
Linen	FA F0 E6
LavenderBlush	FF F0 F5
MistyRose	FF E4 E1
Grey colors
Gainsboro	DC DC DC
LightGrey	D3 D3 D3
Silver	C0 C0 C0
DarkGray	A9 A9 A9
Gray	80 80 80
DimGray	69 69 69
LightSlateGray	77 88 99
SlateGray	70 80 90
DarkSlateGray	2F 4F 4F
Black	00 00 00

Web-safe colors

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Another set of 216 color values are commonly considered to be the "web-safe" color palette; developed at a time when many computer displays were only capable of displaying 256 colors. A set of colors was needed that could be shown without dithering on 256-color displays; the number 216 was chosen partly because computer operating systems customarily reserved sixteen to twenty colors for their own use; it was also selected because it allows exactly six shades each of red, green, and blue. (6 × 6 × 6 = 216). The palette was first identified by Lynda Weinman.

The list of colors is often presented as if it has special properties that render them immune to dithering. In fact, on 256-color displays applications can set a palette of any selection of colors that they choose, dithering the rest. These colors were chosen specifically because they matched the palettes selected by the then leading browser applications. Fortunately, there were not radically different palettes in use in different popular browsers.

"Web-safe" colors had a flaw in that, on systems such as X Windows where the palette is shared between applications, smaller color cubes (5x5x5 or 4x4x4) were often allocated by browsers — thus, the "web safe" colors would actually dither on such systems. Better results were obtained by providing an image with a larger range of colors and allowing the browser to quantize the color space if needed, rather than suffer the quality loss of a double quantization.

By the early years of the 21st century, driven by the needs of video games and digital photos, personal computers typically had at least 16-bit color and usually 24-bit (truecolor). Even mobile devices had at least 16-bit color, driven by the inclusion of cameras on cellphones. The use of "web-safe" colors fell into disuse, but persisted as folklore.

The "web-safe" colors do not have names, but each can be specified by an RGB triplet. In the table below, a three-digit number is used as a shorthand notation for the six-digit hexadecimal numerals above. The digit "3" is equivalent to the hexadecimal numeral "33"; "C" is equivalent to "CC". For example, "F63" in the table below is equivalent to "#FF6633" in the system used previously. Below are the values for the 6 shades of each color out of 256 possible color shades.

6 shades of each color

digit	hexadecimal	decimal
0	00	0
3	33	51
6	66	102
9	99	153
C or (12)	CC	204
F or (15)	FF	255

The following table shows all of the "web-safe" colors, underlining the really-safe (see next section) colors. The lack of gamma correction means that the six desired intensities 0%, 20%, 40%, 60%, 80%, and 100% are displayed as 0%, 2%, 10%, 28%, 57%, and 100% on a standard 2.5 gamma CRT or LCD, making most colors very dark. The intensities at the low end of the range are nearly indistinguishable from each other:

Really web safe colors

Designers were often encouraged to stick to these 216 "web-safe" colors in their websites; however, 8-bit color displays were much more common when the 216-color palette was developed than they are now. David Lehn and Hadley Stern have since discovered that only 22 of the 216 colors in the web-safe palette are reliably displayed without inconsistent remapping on 16-bit computer displays. They called these 22 colors the "really safe" palette; it consists mainly of shades of green and yellow, as can be seen in the table above, where the "really safe" colors are underlined. Death of the Websafe Color Palette? Last accessed on June 24, 2006

CSS colors

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The Cascading Style Sheets language defines the same number of named colors as the HTML 4 spec, namely the 16 listed above. Additionally, CSS 2.1 adds the 'orange' color name to the list:

Color	Hexadecimal
orange	#ffa500

CSS 2, SVG and CSS 2.1 also allow web authors to use so-called system colors, which are color names whose values are taken from the operating system. This enables web authors to style their content in line with the operating system of the user agent. See As of early 2004, it appears that the CSS3 color module will once again drop these values, marking them deprecated, but this may change: [http://www.w3.org/TR/css3-color/#css2-system.

The developing CSS3 specification will also introduce HSL color space values to style sheets:

/* RGB model */ p { color: #f00 } /* #rgb */ p { color: #ff0000 } /* #rrggbb */ p { color: rgb(255,0,0) } /* integer range 0 - 255 */ p { color: rgb(100%, 0%, 0%) } /* float range 0.0% - 100.0% */

/* RGB with alpha channel, added to CSS3 */ p { color: rgba(255,0,0,0.5) /* 0.5 opacity, semi-transparent */

/* HSL model, added to CSS3 */ p { color: hsl(0, 100%, 50%) } /* red */ p { color: hsl(120, 100%, 50%) } /* green */ p { color: hsl(120, 100%, 25%) } /* light green */ p { color: hsl(120, 100%, 75%) } /* dark green */ p { color: hsl(120, 50%, 50%) } /* pastel green */

/* HSL model with alpha channel */ p { color: hsla(120, 100%, 50%, 1) } /* green */ p { color: hsla(120, 100%, 50%, 0.5) } /* semi-transparent green */ p { color: hsla(120, 100%, 50%, 0.1) } /* very transparent green */

Accessibility

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• Some browsers and devices don't support colors.
• For blind and colorblind users Web content depending on colors can be unusable or difficult to use.
• Mixing legacy markup like bgcolor with modern CSS fails for legacy browsers not supporting CSS.
• The shorthand #RGB as in bgcolor="#0FF" does not work with some browsers, it should be #RRGGBB as in bgcolor="#00FFFF".
• Both foreground and background color should be modified to avoid black on black effects.

Popular browsers show links as shades of blue, dark background colors like blue or navy don't work for such links. Using CSS to modify link colors cannot work with legacy browsers. The Netscape 4.x support for CSS is frequently disabled for being as paltry as it is.

References

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See also

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• List of palettes
• X11 color names
• RGB color space
• hexadecimal
• Color tool
• HTML and CSS
• color
• RGB color model
• alphabetic list of colors, with samples and codes

External links

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• List of web colors - a more complete list.
• CSS2.1 Color Specification
• Web-Colors-explained.com
• Interactive color changer
• 4096 web colors & hexadecimal codes produced by combining 16 shades of each primary color (Red, Green & Blue)
• XHTML colour names and their sRGB values

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