May 7, 2006

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Html Color Codes

There are places in a wiki where colors can be specified (see ConfigurationFile and CdmlElements). You can specify colors using CdmlColorNames or the more cryptic but universal HtmlColorCodes.

HTML colors are specified by their numerical RGB values using the syntax #RRGGBB. Each of the values representing the red, green or blue part of the resulting color is specified by a hexadecimal number in the range between 00 (decimal 0) and ff (decimal 255). The hexadecimal digits 0,1,2,3,4,5,6,7,8,9,a,b,c,d,e,f represent the decimal numbers 0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15.

Therefore the 3 basic colors are:

 #ff0000 #00ff00 #0000ff

and the 3 combinations of two colors:

 #ffff00 #00ffff #ff00ff

Since each of the values for R, G and B can be in the range between 0 and 255, the resulting number of different colors which can be displayed is: 256 * 256 * 256 = 16.777.216, RGB color codes can be chosen arbitrarily, e.g.

 #af8735 #3789f0 #fedcba

The human eye can only distinguish several thousand shades, therefore the full variety of different RGB colors is seldom used. For example, the following colors are almost impossible to tell apart:

 #eeeee0 #eeeee1 #eeeee2

So it makes sense to restrict oneself to the use of only a limited range of colors. One way is to use only the 16 hexadecimal values 00 11 22 33 44 55 66 77 88 99 aa bb cc dd ee and ff. This results in 4096 different colors.

Please compare the following colors with the ones shown above:

 #aa8833 #3388ee #ffddbb

Although numerically different, you will hardly notice a difference in color.

The next step is to reduce the color-range to only 6 shades per color: 00 33 66 99 cc ff. Then the following 6 x 6 x 6 = 216 colors remain:

 #000000 #000033 #000066 #000099 #0000cc #0000ff #003300 #003333 #003366 #003399 #0033cc #0033ff #006600 #006633 #006666 #006699 #0066cc #0066ff #009900 #009933 #009966 #009999 #0099cc #0099ff #00cc00 #00cc33 #00cc66 #00cc99 #00cccc #00ccff #00ff00 #00ff33 #00ff66 #00ff99 #00ffcc #00ffff #330000 #330033 #330066 #330099 #3300cc #3300ff #333300 #333333 #333366 #333399 #3333cc #3333ff #336600 #336633 #336666 #336699 #3366cc #3366ff #339900 #339933 #339966 #339999 #3399cc #3399ff #33cc00 #33cc33 #33cc66 #33cc99 #33cccc #33ccff #33ff00 #33ff33 #33ff66 #33ff99 #33ffcc #33ffff #660000 #660033 #660066 #660099 #6600cc #6600ff #663300 #663333 #663366 #663399 #6633cc #6633ff #666600 #666633 #666666 #666699 #6666cc #6666ff #669900 #669933 #669966 #669999 #6699cc #6699ff #66cc00 #66cc33 #66cc66 #66cc99 #66cccc #66ccff #66ff00 #66ff33 #66ff66 #66ff99 #66ffcc #66ffff #990000 #990033 #990066 #990099 #9900cc #9900ff #993300 #993333 #993366 #993399 #9933cc #9933ff #996600 #996633 #996666 #996699 #9966cc #9966ff #999900 #999933 #999966 #999999 #9999cc #9999ff #99cc00 #99cc33 #99cc66 #99cc99 #99cccc #99ccff #99ff00 #99ff33 #99ff66 #99ff99 #99ffcc #99ffff #cc0000 #cc0033 #cc0066 #cc0099 #cc00cc #cc00ff #cc3300 #cc3333 #cc3366 #cc3399 #cc33cc #cc33ff #cc6600 #cc6633 #cc6666 #cc6699 #cc66cc #cc66ff #cc9900 #cc9933 #cc9966 #cc9999 #cc99cc #cc99ff #cccc00 #cccc33 #cccc66 #cccc99 #cccccc #ccccff #ccff00 #ccff33 #ccff66 #ccff99 #ccffcc #ccffff #ff0000 #ff0033 #ff0066 #ff0099 #ff00cc #ff00ff #ff3300 #ff3333 #ff3366 #ff3399 #ff33cc #ff33ff #ff6600 #ff6633 #ff6666 #ff6699 #ff66cc #ff66ff #ff9900 #ff9933 #ff9966 #ff9999 #ff99cc #ff99ff #ffcc00 #ffcc33 #ffcc66 #ffcc99 #ffcccc #ffccff #ffff00 #ffff33 #ffff66 #ffff99 #ffffcc #ffffff

This 216 color palette has become popular years ago, because the first generation of color-PCs was just able to display it. For webdesigners this was an acceptable compromise solution. So these colors are still preferred by some webdesigners even nowadays.

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