These images are generally used for line drawings,
images of text, logos, or cartoons??”anything that doesn??™t require thousands of colors for a smooth color
blend, such as a photograph. With a proper graphics tool like Adobe Fireworks, you can reduce the number
of colors in a GIF image to a minimum, thereby compressing the file and reducing download time.
The GIF format has two varieties: regular (technically, GIF87a) and an enhanced version known as GIF89a.
This improved GIF file brings three important attributes to the format. First, GIF89a supports transparency,
whereby one or more colors can be set to automatically match the background color of the page containing
the image. This property is necessary for creating nonrectangular-appearing images. Whenever you see a
round or irregularly shaped logo or illustration on the Web, a rectangular frame is displayed as the image is
loading??”this is the actual size and shape of the graphic. The colors surrounding the irregularly shaped
central image are set to transparent in a graphics-editing program (such as Adobe Fireworks or Adobe
Photoshop) before the image is saved in GIF89a format.
Most of the latest versions of the popular graphic tools default to using GIF89a, so unless
you??™re working with older, legacy images, you??™re not too likely to encounter the less flexible
GIF87a format.
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