X11 color names
Encyclopedia
In computing
Computing
Computing is usually defined as the activity of using and improving computer hardware and software. It is the computer-specific part of information technology...

, on the X Window System
X Window System
The X window system is a computer software system and network protocol that provides a basis for graphical user interfaces and rich input device capability for networked computers...

, X11 color names are represented in a simple text file, which maps certain strings to RGB color
Color
Color or colour is the visual perceptual property corresponding in humans to the categories called red, green, blue and others. Color derives from the spectrum of light interacting in the eye with the spectral sensitivities of the light receptors...

 values. It is shipped with every X11 installation, hence the name, and is usually located in <X11root>/lib/X11/rgb.txt.

It is not known who originally compiled the list. The list does not show a continuity either in selected color values or in color name
Color name
A color term, also known as a color name, is a word or phrase that refers to a specific color. The color term may refer to human perception of that color , or to an underlying physical property...

s, and many color triplets have multiple names. Despite this, graphic designers and others got used to them, making it practically impossible to introduce a different list. In some applications multipart names are written with spaces, in others joined together, often in camel case; this article uses spaces and uppercase initials.

The first versions of Mosaic
Mosaic (web browser)
Mosaic is the web browser credited with popularizing the World Wide Web. It was also a client for earlier protocols such as FTP, NNTP, and gopher. Its clean, easily understood user interface, reliability, Windows port and simple installation all contributed to making it the application that opened...

 and Netscape Navigator
Netscape Navigator
Netscape Navigator was a proprietary web browser that was popular in the 1990s. It was the flagship product of the Netscape Communications Corporation and the dominant web browser in terms of usage share, although by 2002 its usage had almost disappeared...

 used the X11 colors as the basis for the Web colors
Web colors
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 ....

 list, as both were originally X applications. The W3C
World Wide Web Consortium
The World Wide Web Consortium is the main international standards organization for the World Wide Web .Founded and headed by Tim Berners-Lee, the consortium is made up of member organizations which maintain full-time staff for the purpose of working together in the development of standards for the...

 specifications SVG and CSS level 3 module Color
CSS
-Computing:*Cascading Style Sheets, a language used to describe the style of document presentations in web development*Central Structure Store in the PHIGS 3D API*Closed source software, software that is not distributed with source code...

 eventually adopted the X11 list with some changes, as did JavaScript 1.1
JavaScript
JavaScript is a prototype-based scripting language that is dynamic, weakly typed and has first-class functions. It is a multi-paradigm language, supporting object-oriented, imperative, and functional programming styles....

. It is a superset of the 16 “VGA colors” defined in HTML 3.2 and CSS level 1.

Color name clashes

Perhaps most unusual of the color clashes between X11 and W3C is the case of ‘Gray’. In HTML, ‘Gray’ is specifically reserved for the 128 triplet, i.e. 50% gray. However, in X11, ‘gray’ was assigned to the 190 triplet, i.e. 75%, which is close to W3C ‘Silver’, and had ‘Light Gray’ at 211 and ‘Dark Gray’ at 169 counterparts. This resulted in W3C’s ‘Gray’, at 50%, actually being significantly darker than ‘Dark Gray’, at 66%.

The W3C also defined a color that is equal to X11’s ‘Green’, but called it ‘Lime’.
Color name X11 color W3C color
red green blue Sample Sample red green blue
Gray 75% 75% 75%     50% 50% 50%
Green
Green
Green is a color, the perception of which is evoked by light having a spectrum dominated by energy with a wavelength of roughly 520–570 nanometres. In the subtractive color system, it is not a primary color, but is created out of a mixture of yellow and blue, or yellow and cyan; it is considered...

0% 100% 0%     0% 50% 0%
Maroon
Maroon (color)
Maroon is a dark red color.-Etymology:Maroon is derived from French marron .The first recorded use of maroon as a color name in English was in 1789.-Maroon :...

69% 19% 38%     50% 0% 0%
Purple
Purple
Purple is a range of hues of color occurring between red and blue, and is classified as a secondary color as the colors are required to create the shade....

63% 13% 94%     50% 0% 50%

Color name charts

These charts are not a standard set of colors to be found on any X Window system. Rather it is the standardised X11 color names accepted by browsers following W3C standards. This set is cut down and rationalised, and has a few differences from a typical rgb.txt file. RGB values shown are normalised to the 8-bit integer range 0 to 255.



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Shades of gray

The list shown above covers only the colors supported by popular browsers. Some browsers like Netscape navigator
Netscape Navigator
Netscape Navigator was a proprietary web browser that was popular in the 1990s. It was the flagship product of the Netscape Communications Corporation and the dominant web browser in terms of usage share, although by 2002 its usage had almost disappeared...

 insisted on an ‘a’ in any ‘Gray’ except for ‘Light Grey’.

The complete rgb.txt defines 101 shades from ‘Gray 0’ (black) up to ‘Gray 100’ (white) in addition to ‘Gray’ and its variants listed above. The shades are apparently defined by the formula Gray N := round(N% × 255) resulting in e.g. ‘Gray 96’ , which happens to be the same as ‘White Smoke’. Similarly ‘Dim Gray’ is the same as ‘Gray 41’ .

On the other hand ‘Gray’ lies between ‘Gray 74’ and ‘Gray 75’ , ‘Dark Gray’ is not the same as ‘Gray 66’ , and ‘Light Grey’ is not the same as ‘Gray 83’ .

Color variations

For 78 colors as listed above, rgb.txt offers four variants ‘color 1’, ‘color 2’, ‘color 3’, and ‘color 4’, with ‘color 1’ corresponding to ‘color’, so e.g. ‘Snow 1’ is the same as ‘Snow’. These variations are neither supported by popular browsers nor adopted by W3C standards.

The formulae used to determine the RGB values for these variations appear to be somewhere near
color 2 := color × 93.2%
color 3 := color × 80.4%
color 4 := color × 54.8%

Examples:
  • 205.2 = 255 × 80.4/100 and 192.96 = 240 × 80.4/100 explain ‘Ivory 3’ (205, 205, 196) based on ‘Ivory’ (255, 255, 240).
  • 139.74 = 255 × 54.8/100 and 131.52 = 240 × 54.8/100 are close to ‘Azure 4’ (131, 139, 139) based on ‘Azure’ (240, 255, 255).
  • 237.66 = 255 × 93.2/100 yields ‘Yellow 2’ (238, 238, 0) based on ‘Yellow’ (255, 255 ,0).

External links

The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
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