(Graphics Interchange Format) A popular bitmapped graphics file format developed by CompuServe. Pronounced "giff" with a hard "g" by most Mac users and "jiff" by PC users, GIFs are widely used on the Web because the format uses its own form of compression.
GIF supports 8-bit color (256 colors), but gets the most mileage out of its limited colors by using a built-in color palette. For example, the palette for an image of a forest would mostly contain shades of green and brown. If colors are within a tight range, this method provides extraordinary realism in an 8-bit image. See indexed color.
GIF87a and GIF89a
There are two GIF versions: the original GIF87a and subsequent GIF89a, both named after their year of introduction. GIF89a allows one of the colors to be made transparent (see alpha channel) and take on the background color of the underlying page or window. GIF89a also supports animated GIFs, which use multiple frames in sequence to simulate movement (see animated GIF).
GIFs and JPEGs
Both GIF and JPEG images are widely used on the Web and are supported by all Web software that displays graphics. Charts, screen shots and technical drawings with text are typically GIFs (8-bit). Photographs are generally better rendered as JPEGs (24-bit). See JPEG, graphics formats and GIF patents.
At first glance, it looks like the Android robot logo is only green, white and black. Zooming into one of its antennas (middle) shows more shades (see
The GIF format picks the 256 most used colors in an image. Notice how the colors in the palettes match the two images.
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