MACROMEDIA FIREWORKS MX 2004-USING FIREWORKS Use Manual page 237

Removing unused colors
Removing unused colors from an image before exporting or saving makes its file size smaller.
Note: This option is available only for GIFs and other 8-bit graphic file formats.
To remove unused colors:
•
Choose Remove Unused Colors from the Optimize panel Options menu.
To include all colors in the palette, including colors that are not present in the exported or
saved image:
•
Deselect Remove Unused Colors.
Dithering to approximate lost colors
Dithering approximates colors not in the current palette by alternating similarly colored pixels.
From a distance, the colors blend to create the appearance of the missing color. Dithering is
especially helpful when exporting images with complex blends or gradients or when exporting
photographic images to an 8-bit graphic file format such as GIF.
Dithering can greatly increase file size.
Note: The dithering option is available only for GIFs, other 8-bit graphic file formats, and WBMPs.
To dither a graphic:
•
Enter a percentage value in the Dither text box of the Optimize panel.
Viewing colors in a palette
The color table in the Optimize panel displays colors in the current preview when you are
working in 8-bit color or less and lets you modify an image's palette. The color table updates
automatically when you are in Preview mode. It appears empty if you are optimizing more than
one slice at a time or if you are not optimizing in an 8-bit format such as GIF.
Optimizing in the workspace 237