Adobe Fireworks CS3 Manuale Utente
ADOBE FIREWORKS CS3
User Guide
267
To select a color depth:
❖
Select an option from the Colors pop-up menu in the Optimize panel or type a value in the text box. You can select
from 2 to 256 colors.
Note: The actual colors in the image could be lower than the maximum number of colors you select. The number at the
bottom of the color table indicates the actual number of colors visible in the image. If no number is visible, you’ll see a
Rebuild button, which indicates you should rebuild the color palette. For more information, see “Viewing colors in a
palette” on page 268.
bottom of the color table indicates the actual number of colors visible in the image. If no number is visible, you’ll see a
Rebuild button, which indicates you should rebuild the color palette. For more information, see “Viewing colors in a
palette” on page 268.
To select a color depth beyond 256 colors:
❖
Select a 24- or 32-bit file format from the Export File Format pop-up menu in the Optimize panel.
Note: Higher color depths create larger files and are typically not ideal for web graphics. Use only 24- or 32-bit color
depths when exporting or saving photographic images with continuous tones or complex gradient blends of colors. For
high-color-depth graphics on the web, use JPEG files. For more information, see “Optimizing JPEGs” on page 272.
depths when exporting or saving photographic images with continuous tones or complex gradient blends of colors. For
high-color-depth graphics on the web, use JPEG files. For more information, see “Optimizing JPEGs” on page 272.
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:
❖
Select 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.
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.