Causing a displayed or printed image to appear more photographic by inserting shades of gray or color. Dithering simulates more colors and shades in a palette than actually exist.
While dithering cannot produce the identical results as having sufficient levels of gray or colors in the graphics display system (the color depth), it can make shaded drawings and photographs appear extremely realistic. See
color depth,
24-bit color and
halftone.
Dithering is also widely used to smooth curves and diagonals (see
anti-aliasing).
Dithering a Color Image
An infinite palette of colors can be created by using varying shades in adjacent pixels. The right side is a magnification of the left.
Text Is Also Dithered
At the top of this example, the dithered word DATABASE is softer than the undithered word below. The magnified view shows the lighter blue pixels filling in the curves. Dithering on curves and diagonals is called "anti-aliasing."
More Shades Than You Think
At a quick glance, this Android logo appears to be solid green, white and black. However, the magnified view of one of the antennas shows otherwise. See
GIF.