Web colors

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Web colors are colors used in designing web pages, and the methods for describing and specifying those colors. Hexadecimal color codes begin with a hash (#).^[1][2]

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.^[3]

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.^[4] 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

A hex triplet is a six-digit, three-byte hexadecimal number used in HTML, CSS, SVG, 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. Thus web colors specify colors in the Truecolor (24-bit RGB) color scheme. The hex triplet is formed by concatenating three bytes in hexadecimal notation, in the following order:

Byte 1: red value (color type red)

Byte 2: green value (color type green)

Byte 3: blue value (color type blue)

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 equivalent to the hexadecimal numbers 24, 68 and A0 respectively. The hex triplet is obtained by concatenating the 6 hexadecimal digits together, 2468A0 in this example.

Note that if any one of the three color values is less than 16 (decimal) or 10 (hex), it must be represented with a leading zero so that the triplet always has exactly six digits. For example, the decimal triplet 4, 8, 16 would be represented by the hex digits 04, 08, 10, forming the hex triplet 040810.

The number of colors that can be represented by this system is 256 × 256 × 256 = 16,777,216.

An abbreviated, three (hexadecimal) digit form is sometimes used.^[5] Expanding this form to the six-digit form is as simple as doubling each digit: 09C becomes 0099CC. This allows each color value to cover its full range from 00 to FF. The three-digit form is described in the CSS specification, not in HTML. As a result, the three digit form in an attribute other than "style" is not interpreted as a valid color in some browsers.

Converting RGB to hexadecimal

See also: Hexadecimal#Converting from other bases

RGB values are usually given in the 0–255 range; if they are in the 0–1 range, the values are multiplied by 255 before conversion. This number divided by 16 (integer division; ignoring any remainder) gives us the first hexadecimal digit (between 0 and F, where the letters A to F represent the numbers 10 to 15. See hexadecimal for more details). The remainder gives us the second hexadecimal digit. For instance the RGB value 201 divides into 12 groups of 16, thus the first digit is C. A remainder of 9 gives us the hexadecimal number C9. This process is repeated for each of the three color values.

Conversion between number bases is a common feature of calculators, including both hand-held models and the software calculators bundled with most modern operating systems. Web-based tools specifically for converting color values are also available.^[6]

HTML color names

Main article: HTML color names

The HTML 4.01 specification^[7] defines sixteen named colors, as follows (names are defined in this context to be case-insensitive):

CSS 1–2.0 / HTML 3.2–4 / VGA color names

Name	Hex triplet	Red	Green	Blue	Hue	Satur	Light	Satur	Value	CGA number (name); alias
White	#FFFFFF	100%	100%	100%	&100000000000000000000000°	0%	100%	0%	100%	15 (white)
Silver	#C0C0C0	75%	75%	75%	&100000000000000000000000°	0%	75%	0%	75%	07 (light gray)
Gray	#808080	50%	50%	50%	&100000000000000000000000°	0%	50%	0%	50%	08 (dark gray)
Black	#000000	0%	0%	0%	&100000000000000000000000°	0%	0%	0%	0%	00 (black)
Red	#FF0000	100%	0%	0%	&100000000000000000000000°	100%	50%	100%	100%	12 (high red)
Maroon	#800000	50%	0%	0%	&100000000000000000000000°	100%	25%	100%	50%	04 (low red)
Yellow	#FFFF00	100%	100%	0%	&1000000000000006000000060°	100%	50%	100%	100%	14 (yellow)
Olive	#808000	50%	50%	0%	&1000000000000006000000060°	100%	25%	100%	50%	06 (brown)
Lime	#00FF00	0%	100%	0%	&10000000000000120000000120°	100%	50%	100%	100%	10 (high green); green
Green	#008000	0%	50%	0%	&10000000000000120000000120°	100%	25%	100%	50%	02 (low green)
Aqua	#00FFFF	0%	100%	100%	&10000000000000180000000180°	100%	50%	100%	100%	11 (high cyan); cyan
Teal	#008080	0%	50%	50%	&10000000000000180000000180°	100%	25%	100%	50%	03 (low cyan)
Blue	#0000FF	0%	0%	100%	&10000000000000240000000240°	100%	50%	100%	100%	09 (high blue)
Navy	#000080	0%	0%	50%	&10000000000000240000000240°	100%	25%	100%	50%	01 (low blue)
Fuchsia	#FF00FF	100%	0%	100%	&10000000000000300000000300°	100%	50%	100%	100%	13 (high magenta); magenta
Purple	#800080	50%	0%	50%	&10000000000000300000000300°	100%	25%	100%	50%	05 (low magenta)

These 16 were labelled as sRGB and included in the HTML 3.0 specification, which noted they were "the standard 16 colors supported with the Windows VGA palette."^[8]

X11 color names

Main article: X11 color names

In addition, a number of colors are defined by web browsers. A particular browser may not recognize all of these colors, but as of 2005 all modern general-use browsers support the full list of colors. 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 space), 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.^[9]

The list of web "X11 colors" from the CSS3 specification, along with their hexadecimal and decimal equivalents, is shown below, compare the alphabetical lists in the W3C standards. Note that this includes the common synonyms: aqua (HTML4/CSS 1.0 standard name) and cyan (common sRGB name), magenta (common sRGB name) and fuchsia (HTML4/CSS 1.0 standard name), gray (HTML4/CSS 1.0 standard name) and grey. ^[10][11]

HTML name Hex code R   G   B Decimal code R   G   B Red colors IndianRed CD 5C 5C 205  92  92 LightCoral F0 80 80 240 128 128 Salmon FA 80 72 250 128 114 DarkSalmon E9 96 7A 233 150 122 LightSalmon FF A0 7A 255 160 122 Red FF 00 00 255   0   0 Crimson DC 14 3C 220  20  60 FireBrick B2 22 22 178  34  34 DarkRed 8B 00 00 139   0   0 Pink colors Pink FF C0 CB 255 192 203 LightPink FF B6 C1 255 182 193 HotPink FF 69 B4 255 105 180 DeepPink FF 14 93 255  20 147 MediumVioletRed C7 15 85 199  21 133 PaleVioletRed DB 70 93 219 112 147 Orange colors LightSalmon FF A0 7A 255 160 122 Coral FF 7F 50 255 127  80 Tomato FF 63 47 255  99  71 OrangeRed FF 45 00 255  69   0 DarkOrange FF 8C 00 255 140   0 Orange FF A5 00 255 165   0 Yellow colors Gold FF D7 00 255 215   0 Yellow FF FF 00 255 255   0 LightYellow FF FF E0 255 255 224 LemonChiffon FF FA CD 255 250 205 LightGoldenrodYellow FA FA D2 250 250 210 PapayaWhip FF EF D5 255 239 213 Moccasin FF E4 B5 255 228 181 PeachPuff FF DA B9 255 218 185 PaleGoldenrod EE E8 AA 238 232 170 Khaki F0 E6 8C 240 230 140 DarkKhaki BD B7 6B 189 183 107 Purple colors Lavender E6 E6 FA 230 230 250 Thistle D8 BF D8 216 191 216 Plum DD A0 DD 221 160 221 Violet EE 82 EE 238 130 238 Orchid DA 70 D6 218 112 214 Fuchsia FF 00 FF 255   0 255 Magenta FF 00 FF 255   0 255 MediumOrchid BA 55 D3 186  85 211 MediumPurple 93 70 DB 147 112 219 BlueViolet 8A 2B E2 138  43 226 DarkViolet 94 00 D3 148   0 211 DarkOrchid 99 32 CC 153  50 204 DarkMagenta 8B 00 8B 139   0 139 Purple 80 00 80 128   0 128 Indigo 4B 00 82  75   0 130 DarkSlateBlue 48 3D 8B  72  61 139 SlateBlue 6A 5A CD 106  90 205 MediumSlateBlue 7B 68 EE 123 104 238

HTML name Hex code R   G   B Decimal code R   G   B Green colors GreenYellow AD FF 2F 173 255  47 Chartreuse 7F FF 00 127 255   0 LawnGreen 7C FC 00 124 252   0 Lime 00 FF 00   0 255   0 LimeGreen 32 CD 32  50 205  50 PaleGreen 98 FB 98 152 251 152 LightGreen 90 EE 90 144 238 144 MediumSpringGreen 00 FA 9A   0 250 154 SpringGreen 00 FF 7F   0 255 127 MediumSeaGreen 3C B3 71  60 179 113 SeaGreen 2E 8B 57  46 139  87 ForestGreen 22 8B 22  34 139  34 Green 00 80 00   0 128   0 DarkGreen 00 64 00   0 100   0 YellowGreen 9A CD 32 154 205  50 OliveDrab 6B 8E 23 107 142  35 Olive 80 80 00 128 128   0 DarkOliveGreen 55 6B 2F  85 107  47 MediumAquamarine 66 CD AA 102 205 170 DarkSeaGreen 8F BC 8F 143 188 143 LightSeaGreen 20 B2 AA  32 178 170 DarkCyan 00 8B 8B   0 139 139 Teal 00 80 80   0 128 128 Blue/Cyan colors Aqua 00 FF FF   0 255 255 Cyan 00 FF FF   0 255 255 LightCyan E0 FF FF 224 255 255 PaleTurquoise AF EE EE 175 238 238 Aquamarine 7F FF D4 127 255 212 Turquoise 40 E0 D0  64 224 208 MediumTurquoise 48 D1 CC  72 209 204 DarkTurquoise 00 CE D1   0 206 209 CadetBlue 5F 9E A0  95 158 160 SteelBlue 46 82 B4  70 130 180 LightSteelBlue B0 C4 DE 176 196 222 PowderBlue B0 E0 E6 176 224 230 LightBlue AD D8 E6 173 216 230 SkyBlue 87 CE EB 135 206 235 LightSkyBlue 87 CE FA 135 206 250 DeepSkyBlue 00 BF FF   0 191 255 DodgerBlue 1E 90 FF  30 144 255 CornflowerBlue 64 95 ED 100 149 237 RoyalBlue 41 69 E1  65 105 225 Blue 00 00 FF   0   0 255 MediumBlue 00 00 CD   0   0 205 DarkBlue 00 00 8B   0   0 139 Navy 00 00 80   0   0 128 MidnightBlue 19 19 70  25  25 112

HTML name Hex code R   G   B Decimal code R   G   B Brown colors Cornsilk FF F8 DC 255 248 220 BlanchedAlmond FF EB CD 255 235 205 Bisque FF E4 C4 255 228 196 NavajoWhite FF DE AD 255 222 173 Wheat F5 DE B3 245 222 179 BurlyWood DE B8 87 222 184 135 Tan D2 B4 8C 210 180 140 RosyBrown BC 8F 8F 188 143 143 SandyBrown F4 A4 60 244 164  96 Goldenrod DA A5 20 218 165  32 DarkGoldenrod B8 86 0B 184 134  11 Peru CD 85 3F 205 133  63 Chocolate D2 69 1E 210 105  30 SaddleBrown 8B 45 13 139  69  19 Sienna A0 52 2D 160  82  45 Brown A5 2A 2A 165  42  42 Maroon 80 00 00 128   0   0 White colors White FF FF FF 255 255 255 Snow FF FA FA 255 250 250 Honeydew F0 FF F0 240 255 240 MintCream F5 FF FA 245 255 250 Azure F0 FF FF 240 255 255 AliceBlue F0 F8 FF 240 248 255 GhostWhite F8 F8 FF 248 248 255 WhiteSmoke F5 F5 F5 245 245 245 Seashell FF F5 EE 255 245 238 Beige F5 F5 DC 245 245 220 OldLace FD F5 E6 253 245 230 FloralWhite FF FA F0 255 250 240 Ivory FF FF F0 255 255 240 AntiqueWhite FA EB D7 250 235 215 Linen FA F0 E6 250 240 230 LavenderBlush FF F0 F5 255 240 245 MistyRose FF E4 E1 255 228 225 Gray colors Gainsboro DC DC DC 220 220 220 LightGrey D3 D3 D3 211 211 211 Silver C0 C0 C0 192 192 192 DarkGray A9 A9 A9 169 169 169 Gray 80 80 80 128 128 128 DimGray 69 69 69 105 105 105 LightSlateGray 77 88 99 119 136 153 SlateGray 70 80 90 112 128 144 DarkSlateGray 2F 4F 4F  47  79  79 Black 00 00 00   0   0   0

Web-safe colors

Color depth
1-bit monochrome 8-bit grayscale 8-bit color 15/16-bit color (High color) 24-bit color (True color) 30/36/48-bit color (Deep color)
Related
Indexed color Palette RGB color model Web-safe color
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At one time many computer displays were only capable of displaying 256 colors. These may be dictated by the hardware or changeable by a "color table". When a color is found (e.g., in an image) that is not one available, a different one has to be used. This can be either using the closest color (fast) or dithering (slow, looks better).

There were various attempts to make a "standard" color palette. 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 equally-spaced shades of red, green, and blue (6 × 6 × 6 = 216), each from 00 to FF (including both limits).

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.^{[citation needed]}

"Web-safe" colors had a flaw in that, on systems such as X11 where the palette is shared between applications, smaller color cubes (5×5×5 or 4×4×4) 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.

As of 2011^[update], personal computers typically^[12] have 24-bit (TrueColor) and the use of "web-safe" colors has fallen into practical disuse. Even mobile devices have at least 16-bit color, driven by the inclusion of cameras on cellphones.

The "web-safe" colors do not all have standard names, but each can be specified by an RGB triplet: each component (red, green, and blue) takes one of the six values from the following table (out of the 256 possible values available for each component in full 24-bit color).

6 shades of each color

Key	Hex	Decimal	Fraction
0	00	0	0
3	33	51	0.2
6	66	102	0.4
9	99	153	0.6
C or (12)	CC	204	0.8
F or (15)	FF	255	1

The following table shows all of the "web-safe" colors, underlining the really-safe colors. (One shortcoming of the web-safe palette is its poor selection of light background colors.) The intensities at the low end of the range, especially the two darkest, are often hard to distinguish.

Color table

In the table below, each color code listed is a short-hand for the RGB value; for example, code 609 is equivalent to RGB code 102-0-153 or HEX code #660099.

Web-Safe Colors

*000*	300	600	900	C00	*F00*
*003*	303	603	903	C03	*F03*
006	306	606	906	C06	F06
009	309	609	909	C09	F09
00C	30C	60C	90C	C0C	F0C
*00F*	30F	60F	90F	C0F	*F0F*
030	330	630	930	C30	F30
033	333	633	933	C33	F33
036	336	636	936	C36	F36
039	339	639	939	C39	F39
03C	33C	63C	93C	C3C	F3C
03F	33F	63F	93F	C3F	F3F
060	360	660	960	C60	F60
063	363	663	963	C63	F63
066	366	666	966	C66	F66
069	369	669	969	C69	F69
06C	36C	66C	96C	C6C	F6C
06F	36F	66F	96F	C6F	F6F
090	390	690	990	C90	F90
093	393	693	993	C93	F93
096	396	696	996	C96	F96
099	399	699	999	C99	F99
09C	39C	69C	99C	C9C	F9C
09F	39F	69F	99F	C9F	F9F
0C0	3C0	6C0	9C0	CC0	FC0
0C3	3C3	6C3	9C3	CC3	FC3
0C6	3C6	6C6	9C6	CC6	FC6
0C9	3C9	6C9	9C9	CC9	FC9
0CC	3CC	6CC	9CC	CCC	FCC
0CF	3CF	6CF	9CF	CCF	FCF
*0F0*	3F0	*6F0*	9F0	CF0	*FF0*
0F3	*3F3*	*6F3*	9F3	CF3	*FF3*
*0F6*	*3F6*	6F6	9F6	*CF6*	*FF6*
0F9	3F9	6F9	9F9	CF9	FF9
*0FC*	*3FC*	6FC	9FC	CFC	FFC
*0FF*	*3FF*	*6FF*	9FF	CFF	*FFF*

Safest web 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.^[13]

CSS colors

The Cascading Style Sheets language defines the same number of named colors as the HTML 4 spec, namely the 16 listed previously. Additionally, CSS 2.1 adds the 'orange' color name to the list^[14]:

Colors added in CSS 2.1

Name	Hex triplet	Red	Green	Blue	Hue	Satur	Light	Satur	Value	Alias
orange	#FFA500	100%	65%	0%	&1000000000000003900000039°	100%	50%	—%	—%

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.^[15] As of early 2004^[update], it appears that the CSS3 color module will once again drop these values, marking them deprecated, but this may change.^[16]

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%) } /* dark green */
p { color: hsl(120, 100%, 75%) } /* light 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

Some browsers and devices do not support colors. For these blind and colorblind users, Web content depending on colors can be unusable or difficult to use. Both foreground and background color should be modified to avoid black on black effects.^[17] Similarly, most browsers show links as shades of blue by default; therefore, dark background colors, such as blue or navy, do not display well for such links.

See also

	Color portal
	Computer graphics portal

• Color tool
• List of colors
• List of color palettes
• CIE 1931 XYZ color space
• CIE L*a*b* color space
• Wide Gamut RGB color space
• ProPhoto RGB
• Adobe RGB color space
• scRGB
• sRGB
• RGB color space

References

1. ^ Niederst Robbins, Jennifer. Web Design in a Nutshell, p. 103.
2. ^ York, Richard. Beginning CSS, pp. 71–72.
3. ^ Guide to Graphics. SP LUS, splus.com. Page 13.
4. ^ Digital Color Imaging Handbook By Gaurav Sharma. ISBN 084930900X
5. ^ CSS3 color module
6. ^ RGB to Hexadecimal Color Converter
7. ^ HTML 4.01 Specification section 6.5 "Colors"
8. ^ HTML 3.2 Specification "The BODY element"
9. ^ Public discussion on SVG mailing list Re: color names in SVG-1.0 conflict with /usr/lib/X11/rgb.txt
10. ^ W3C TR CSS3 Color Module, SVG color keywords
11. ^ W3C TR SVG 1.0, recognized color keyword names
12. ^ http://www.w3schools.com/browsers/browsers_display.asp
13. ^ Death of the Websafe Color Palette?
14. ^ "CSS 2.1 Specification: Syntax and basic data types: Colors". 2009-09-08. http://www.w3.org/TR/CSS21/syndata.html#color-units. Retrieved 2009-12-21. 
15. ^ User interface - System colors
16. ^ CSS3 Color Module - CSS2 System Colors
17. ^ If You Pick One Color, Pick Them All

External links

• 4,096 Web-Safe Colors
• CSS2.1 Color Specification
• Sortable Table of X11 Colors
• Web colors at the Open Directory Project
• X11/browser colors, with closest web-safe equivalents
• Color hex codes with rgb chart graph