Web Design in a Nutshell, 3rd Edition

Other Options

The following are descriptions of other aspects of animated GIF files that can be set within most animation programs.

Loop

You can specify the number of times an animation repeats—none, forever, or a specific number. As noted earlier, not all browsers support a specific number of loops (the animation either loops or does not). One workaround to this problem is to build looping right into a file by repeating the frame sequence a number of times; of course, this increases the file size and download time.

Interlaced

Like ordinary GIF89a graphics, you can set animated GIFs to interlace, which causes them to display in a series of passes (starting blocky, finishing clear). It is recommended that you leave the interlacing option set to No or Off, because each frame is on the screen for only a short amount of time.

Color depth

This option allows you to limit the bit depth of the image to some number less than 8 (the default for GIF). Bit depth and its effect on file size is discussed in detail in Chapter 28. Note that if you select the web (6 × 6 × 6) palette, you will need to keep the bit depth set to 8.

Dithering

Dithering is a way to simulate intermediate color shades. It should be used with continuous-tone images.

Background color

Regardless of what color you select in the background color option, Navigator and Internet Explorer display the background color or image you specify in your HTML page. So, this option doesn’t affect the display of the GIF in a browser, only ...