9.1 Web Animations
A graphic tool often seen on Web pages is the ubiquitous, animated
GIF. This is an image file
format that can contain a sequence of frames combining text, images,
and timing information to create a flip-book-like movie. As you will
see in this chapter animated GIFs are easy to create, edit, and view
in the GIMP.
The GIMP can save animations to several different file formats, but
when making animations for the Web, the choice is limited to GIFs.
GIF stands for Graphics Interchange Format , and GIF format files support a number of features that are
particularly useful for Web graphics.
First, GIF is an eight-bit-per-pixel format, which means that with
careful planning a GIF can be almost always properly displayed on
systems providing only eight bits of color (see
9.5). Second, GIFs allow for
transparency, a feature not supported by JPEG (Joint Photographic
Experts Group), the other principle file format for
images on the Web. Third, GIFs support
interlacing which may be of interest for the transmission of images
over low bandwidth networks. Finally, the GIF format supports layers
and attached layer timing information. This last feature is the one
exploited for GIF animations.