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[The following is the conclusion of our series of excerpts from the glasshaus title, Web Graphics for Non-Designers.]
An artist is often challenged by boundaries, and the Web presents some troubling limitations in the form of bandwidth compromises, varying screen resolutions, and video hardware.
A number of these restrictions relate directly to the realm of color online. A GIF image, for example, increases in size with image complexity and the palette used. Gamma correction defaults change from platform to platform, and contrast can vary across different display types. And to really keep everyone on their toes, the capabilities of video hardware from system to system (most often the number of colors they display) can differ by orders of magnitude.
At a time when 8-bit video cards were commonplace in computers, there arose amid web developers the murky head of the browser-safe palette. First publicized by Lynda Weinman on her web site, lynda.com, known as the web-safe palette, it outlined a set of 216 colors considered safe for usage across the PC and Mac platforms, and Internet Explorer and Netscape Navigator browser applications.
Many among the developer crowd will know that an 8-bit display is capable of showing 256 colors. Of these, the respective PC and Mac platforms reserve 40 for system usage, leaving a subset of 216 that are available on both.
The web-safe palette is not difficult to remember. Its RGB triads specified in decimal format are simply the 256 values (0 is the 256th), spaced evenly over five intervals (that is, divisible by 51). These are 0, 51, 102, 153, 204, and 255. HTML also supports color values in hexadecimal format, and these intervals represented in this format are 00, 33, 66, 99, CC, and FF.
Therefore, a color is web-safe if its decimal representation has each RGB value equal to any of the values divisible by 51. {51,102,255}, {0,204,204}, and {255,153,51} are web-safe colors, while {51,102,104}, {43,72,60}, and {52,103,154} are not. In hexadecimal, #CCFF00, #669900, and #00FFFF are safe, whereas #008822, #FC3293, and #4400CC are not.
The palette itself is included below for reference. You will notice that the selection of colors is extremely limiting; it contains a small number of light and dark colors, and is particularly useless if you are considering a scheme incorporating muted and tinted colors.
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Created: December 16, 2002
Revised: December 16, 2002
URL: http://webreference.com/authoring/languages/html/definitive/3/
