dither If a monitor can't show a certain color, dithering approximates the color by placing close together pixels in colors that the computer can display. For example, shades of gray can be simulated onscreen by combining different ratios of black and white pixels. To save file space, Web graphic designers often limit their images to 256 colors and use dithering to imply other colors. If designers don't do this, and if a computer can't handle the colors, its Web browser may try to dither the image, possibly with unattractive results.