|Safe Color Palette|
Some browsers will dither any color settings that are not a part of the system palette at the user's screen resolution. An image may look fine on a system at 16 bit (65,536) or 24 bit (16,777,216) color depth, but it won't look the same when viewed at 8 bit color depth, since the color scheme will not be displayed as authored.
In order to avoid problems, images used on web pages should only use colors taken from what is known as the "safe browser palette" or "non-dithering palette". This palette consists of 216 colours (256 colors minus the palette entries reserved by the system, and those that vary across different systems -- i.e. Windows/Macintosh platforms. This means that you can be sure that your graphics will display as authored on both Macintosh and Windows platforms.
The safe browser palette uses multiples of 51 (33 in hexadecimal notation) for the Red, Green and Blue components (RGB). So, to be sure that the colors you use will not be dithered, only use #rrggbb triplets made up of components of 33 (00, 33, 66, 99, CC and FF). For instance, "#0066FF" would be a "safe" colour, while "#FFF0FA" wouldn't (as it would be dithered to the nearest safe palette entry (i.e. "#FFFFFF").
Most modern programs that you use for creating your web images support the web safe palette and if not, then perhaps it supports plugins or filters. If not, use the image below and use its color table. Also, when using colors in fonts and backgrounds, try to remember to use the safe web palette.
The safe browser palette is shown below as an example. Right-click on the image and save it to your own disk.
To make things easier, you could also use one of the many free programs available on the Internet. See http://www.nonags.com for lots of good free tools. Without endorsing someone's software, two examples are listed below.
By using the 216 color mode, you are restricted to the safe palette.
Download RGB mixer 1.7 (83 kb)
By Johannes Wallroth [Homepage]
With the neat color picker you can select or check a color anywhere on the screen.
Download Color Cop 4.0 (13 kb)
By Datastic [Homepage]