"What You See Is What You Get" isn't always the case in the world of web graphics. If your computer's color palette is set to display 256 or fewer colors, your browser will probably remap the colors in any image it displays. The browser has its own palette of 256 (or fewer) colors. Any image pixel that is not one of these colors is approximated, either by selecting the nearest color or by the process of dithering. Dithered colors utilize patterns of multi-colored pixels that the human eye tends to perceive as a single color--the color that would result if the component colors were blended together.

This usually works well for photographs and other representations of real-world scenes. Data visualization images, on the other hand, often have large areas rendered in single hues where the artifacts of the color remapping process may be particularly conspicuous. Slicer Dicer images, for example, often include three gray background surfaces forming two "walls" and a "ceiling." If the browser uses the nearest-color approach, two of the background surfaces will often be rendered in the same tone of gray, which tends to interfere with other 3D "clues" designed into the image. If it uses dithering, the background will have a distracting "speckled" appearance.

If you don't see these artifacts, good. Your computer is probably set to view thousands or millions of colors. You don't need to be concerned with these issues. If you do see them and would like to do something about it, here are your options.

	Depending on its operating system and hardware capabilities, you may be able to set your system for viewing MORE THAN 256 colors. Macintosh and MS Windows systems, for example, have a control panel to change this setting. (Note: you may need to restart your computer before the change takes effect.)
	Your browser may allow you to select the color remapping mode, either nearest color or dithering. This won't make the artifacts go away, but you may decide you like one mode better than the other.
	Copy the image from the browser to a more powerful graphics application. Most "paint" programs will render an image using the palette imbedded in the image rather than remap it to some other fixed palette. One way to transfer the image is to use your browser's Save As command to save the image as a GIF file, which subsequently can be opened by the graphics viewer application.